Re: M B dealer
You need a combination of two things: a place that cares about the car and one that knows how to service it. Having a coupon I just had the oil changed by my FLD. While they did almost everything right, I got it back to find the clock had been changed but the FSS not. (used 5W-40 MB "approved" which is good for a warm climate).
NP and I called to let them know that it is the left button and not the right.
Of course except for the Jeep, my other cars are worse. I wouldn't even try a dealer & when I go for parts (some are still available where shared) I get a lot of "whazzat?"s.