I have one to share . . . Went to an MB dealer to take care of "cat converter recall". Brought in my ML320, received a call from SA saying my engine mount had COLLAPSED, not about to collapse or something. Took the ML to other place for 2nd opinion, turned out the SA had flat lied to me, mounts were completely intact.
Another item on that ML320, had some serious engine oil leaking at 110K miles at front of engine. Leak was from timing chain cover, was quoted $2,800 including 12hrs of labor time. Didn't know a thing about car repair, got on the internet searched for it. It was very common known issue. Bought a rubber gasket (known issue - revised rubber gasket was all that's needed) and my $4.00 socket set from HF took 10 minutes, FOR ME!
After a few other issues with MB dealers, I've learn to take care of most things myself at old age of 50 something, haven't been to a dealer's office ever since except for a new vehicle or some parts purchase. I owe big thanks to the SA.