rear noise on 2006 Mercedes-Benz C280 4MATIC

when I sit in the car or someone is sitting in the back seat the car is making a squicky noise. I have tried to see if this noise happends while I drive or go over bumps but I have not noticed anything. I took the car to the dealer and they told me that I need to change the rear heim joints at almost 600.00 dollars. I think they're trying to rip me off. what could this noise be coming from? It sound like the spring on an old mattress while jumping on it!....

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1 answer
why would you go to a dealer? there are plenty of local MB
specialty shops---just ask other MB owners who is the best
and get a second opinion.