ATLANTA -- An exclusive CBS Atlanta hidden camera investigation found car repair shops overcharging customers for unneeded repairs, and in some cases, billing for work they aren't doing.

What's the likelihood you will be taken for a ride? CBS Atlanta took an unmarked car to be inspected by our station mechanic at W.T. Standard. Then we rigged it with three hidden cameras, and took it into random shops across Metro Atlanta so we could see what work was done, and what work was not.

Our producers visited 10 repair shops to get an oil change, and we were up sold at 5 of the ten stores we visited.

"Who wants to be told your breaks are dangerous? Or your steering gone bad," said Bill Cloud from the Governor's Office of Consumer Affairs. "You don't want to be on this expressway when something like that happens."

Cloud said questionable car repairs are the number one complaint his office receives.

"These are tough economic times, and a lot of people are cutting corners that might not cut them otherwise," Cloud continued.

At Xpress Lube on Ponce De Leon Avenue, CBS Atlanta was sold an air filter, power steering flush, and coolant flush that our mechanics said we didn't need, and a rear differential service that Xpress Lube said was needed based on mileage. The differential is the set of gears that transfers the power from the transmission to the tires. The total bill was $275.

When our producer asked which of these repairs were necessary, we were told by an employee, "Everything is necessary. Actually technically I am trying to save you as much as I can."

Our next stop was Xpress Lube in Dunwoody. They sold us rear and front differential and a transfer case service.

"Their fluids need to be changed out, drained, and then fluid put back in," an employee explained.

But they should have been able inspect the rear differential fluid to see that it was clean. We just had it changed at their Atlanta store a few hours before. And our hidden cameras also showed they never did some of the work they charged us for.

Our cameras showed they never flushed the rear differential. All the technician did was fill it with more fluid until it overflowed.

Our hidden cameras and an inspection by our mechanic showed Xpress lube never flushed it. They left dirty fluid in the front differential. Our total charges there were $135.

And at Jiffy Lube in Decatur, we were again sold a rear differential service, as well as a transmission service, and a radiator fluid exchange. All services our mechanics said were unnecessary. Remember, our fluid was clean and had already been serviced twice.

And again, like Xpress Lube, they didn't do a flush like they said they would. They just added more fluid, and charged us for work that was never done. The mechanic could have also inspected the coolant which was flushed the day before, but they up sold us on that service for another $89.

And more disturbing was the T-Tech transmission service they sold us for $119.

"The fluid needs to be replaced in it. The fluid is really dark and dirty," the technician explained.

When our producer asked what happens if we left it in, the technician replied, "You definitely don't want to do that."

The mechanics moved the machine over to the car but our hidden cameras showed they never hooked it up. And an inspection by our own mechanic confirmed they never did the work.

"You would adapt it to these lines right here, so I don't see where they did the flush on it," WT Standard said.

The total bill at Jiffy Lube was $300.

Firestone Complete Auto Care off Druid Hills recommended a slew of services to us, everything from a battery corrosion treatment, to a fuel system tune-up and alignment.

"They found some corrosion on your battery posts," a Firestone employee said.

But our mechanics disagreed.

"There is no corrosion buildup. The posts on the battery look very clean," one of our mechanics said.

When we went back to confirm a second time that we actually needed the work, they swayed us into unnecessary repairs by fear.

"Everything that the technicians over here [recommended], they are pretty concerned. We don't actually allow them to suggest stuff that the vehicle doesn't need," he told us.

Decatur Goodyear off Clairmont Road was our most expensive stop, with recommended repairs totaling more than $1,100. We were recommended to do a front and rear differential service, a transmission flush, and spark plugs. The mechanic told us all of the repairs were urgent.

"(You need to) Definitely start getting some of it done before you have a catastrophe," he warned.

And when we returned to confirm we absolutely needed the repairs, Goodyear tacked another recommendation- a brake fluid flush, on top of the transmission flush.

"The transmission is the one that concerns me the most. Transmission is supposed to be like a red fluid. And this is almost black. And brake fluid is the same way. Brake fluid is supposed to be clear. And it is almost black," Wade at Goodyear told us.

But back at our mechanics, they again said these were unnecessary services.

"There is absolutely nothing wrong with that," WT Standard advises. "The fluid is clear."

So CBS Atlanta Chief Investigative Reporter Wendy Saltzman went back to these repair shops with cameras rolling to confront them about some of the questionable sales tactics they used to make a buck. We're asking the Tough Questions to help save you money the next time you walk through their doors.

Remember at Xpress Lube on Ponce, we were up sold an air filter, a power steering flush, and a coolant flush our mechanics said were completely unnecessary. When we approached the store manager, she defended the services.

"Are you guys over charging customers here?" Saltzman questioned.

"No we are not," the manager replied. "The [repairs] are based on mileage."

The store claimed the services were needed, based solely on the mileage on our car. But the manufacturer's recommendations say at our mileage the only recommendation is to inspect the power steering and coolant fluids.

And up the road at Xpress Lube in Dunwoody, where we were charged for another rear differential flush after we had just had the service done a few hours before at their Atlanta store, they also denied wrongdoing.

"Are you guys overcharging customers for services they don't need?" Saltzman questioned.

"We up sold you for a service you did not need?" the manager responded smiling.

They also tacked on a front differential as well. The problem is our hidden cameras and an independent inspection confirmed neither of the flushes were done.

"You guys didn't do the work, we had hidden cameras on the car, which showed you didn't do the work you were supposed to do," Saltzman told the manager.

To top it off, the technicians left dirty fluid in the front differential of our car.

"We had dirty fluid in the front differential you guys claimed you did. You didn't do the work," Saltzman explained.

"We'll I'm pretty sure, um, I can guarantee you the service was done," the manager argued.

But our hidden camera confirmed they just filled the rear differential with more fluid. They didn't do the flush. But they charged for both services.

"I do not tolerate nor condone that type of service. And the manager and the tech involved have been suspended and demoted," said Xpress Lube Owner Terry Fowler.

Fowler owns of both Xpress Lubes we visited. He suspended the employees, but he still defended some of the services they sold us as being required by mileage.

"After 26 years I would not be in business if we did this," Fowler continued.

But our mechanics and the manufactures recommendations don't call for a coolant or a power steering flush at our mileage-- only an inspection.

"Most people don't service them unless you are having a problem with them," said our Mechanic at WT Standard.

And at Jiffy Lube in Decatur where we were again charged for a rear differential flush that wasn't done, employees ran when we tried to ask them the tough questions.

"Oh, don't put me on camera," said an employee who put her hand up to our camera.

"Is this common practice here to overcharge customers?" Saltzman asked.

"No ma'am, it sure isn't," the Jiffy Lube Manager responded.

"But you guys didn't flush the fluid,” Saltzman questioned.

"Ma'am, if we charged you for it we did the service, the manager argued.” "You charged us for a transmission service you didn't do either," Saltzman replied.

And more disturbing was the video and independent inspection that showed they didn't touch the transmission service they charged us for either.

"If it was the case that that was done, then we will take care of the employees who did this. The company does not condone it. That's all there is to it," said the manager.

We also went back to the Firestone on North Druid Hills with cameras rolling to ask about an unnecessary repairs, like a battery corrosion service and a questionable fuel system repair. But the manager passed off our tough questions to their corporate media reps.

"I am sorry, I can't discuss anything," he said.

And back at Goodyear in Decatur, where they made recommendations totaling more than $1,100, they tried to sell us on the fact that chemical test strips proved our fluid was dirty.

"Look at your coolant, it is turning. It is bad coolant," the technician told us.

"We have had the coolant flushed twice now," Saltzman countered.

The technician replied, "Well, it's showing now your brake fluid needs to be changed out."

Remember the mechanic had originally told us our fluid was black, but our station mechanic said it was clear, and not dirty.

So went back to our independent mechanic to get a second opinion about these test strips.

"The test strips in my opinion are not accurate," Mechanic Scott Kuehl told us. "They are supplied by the chemical companies who sell their products to the dealerships."

Bill Cloud from the Governor's Office of Consumer Affairs says there is one sure way to protect yourself.

"The best protection people have is to have a great relationship with their mechanic," he recommends. "If you think you don't need a repair, walk. Take your car to some other place and at least get it checked."

The five repair shops we visited who didn't over charge us were:

• Mr. Transmission on Peachtree Industrial Blvd.
• Precision Tune on Cheshire Bridge
• Kauffman Tire on Peachtree Road
• Jiffy Lube on Peachtree Industrial
• Xpress Lube on Howell Mill

This is not an endorsement for those stores, but they did not make any excessive recommendations during our visits.

Both Firestone and Jiffy Lube supplied also us with a written response which we have posted on the sidebar located on the upper right of the page.