I've found the smart center staff in Buffalo NY are nice, but the Benz mechanical side is not. I called about a known issue, the tech knew just what the issue was, and setup an appointment a week away so they could "get parts". I went, waited 5 hours for a pretty minor set of things, only to be told that a needed part wasn't in (the one we had discussed on the phone over a week before), and I'd have to come back.
Why I had to wait 5 hours to be told this I'm not sure...