They can probably get the scratches out, but the sad thing is, they will chew away a lot of your clearcoat doing it.
I'm sure that there are some good MB dealer service departments out there. I sure wish that one was in my area. I had a new EClass back in '96. I would take it in for warranty service (alot) and it would be perfectly handwashed with fresh wax. As a customer "SERVICE". They would wash it before returning it. Okay, that's a nice gesture, but the car was perfectly clean and waxed and they'd do a 50 cent car wash and leave spots all over it and was away some of the wax.
What is it about these people? My explanation is that it's attitude. There are some dealers of all brands that have a; go to work, put in eight hours, get by enough not to get fired, and then go home, attitude.
Good luck with getting her looking good again. Stick to your guns.