Always write down the milage on the car, in front of the service writer, when you take your car to the dealer. The "kids" in the service department were driving it on dates, and damaged both the wheels and the fender, and the dealership, not MB, owes you recompense.
Writing the milage down, rather ostentatiosly, usually puts and end to this crap, If there is more two miles or so difference when you pick the car up, demand both usage fees and repairs of any damage you claim. The service workers are NOT entitled to use your car for personal use, not even to go pick up lunch "on a test drive" without your permission.
Get to a good independent shop. Any shop, dealer or otherwise, that damages a car and won't make good before even telling you is doing the same kind of work on your car -- crap.
Hans had to have a fender repaired and painted once on short notice when a car rolled and dented a customers -- told the customer about it on delivery. Shop insurance usually takes care of it, but the shop is liable for any damage they do through carelessness.
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!