If you didn't get satisfaction with the agent you delt with, please try someone else or take your problem to the service manager. I would not blame the whole dealership for one bad event. The alignment is probably right and the agent is probably most interested in assuring you of that. They should have no trouble with the aesthetics.
I think one of our members is a tech at that dealership. I guarantee that anyone using him would get special attention.
Please remember that every business is the sum total of thousands of events. Some go wrong. The best of businesses are not perfect, but the best make sure they take care of their problems. I guarantee that their business plan is to fix these problems (Mercedes would have it no other way). Sometimes as businessmen we fail. Most of us would fix it if emotions didn't get in the way. Be professional, and expect it in service. Calmly take your case to a different venue if you get no where with your agent. Try not to make a battle out of it. They really want you to be happy. It is to their benefit. Don't let your relationship with any single person drive you away.
Then again, independent businesses such as mine have thrived on making the personal relationship work along with the technical one. My advice to anyone is to calmly address the problem, most shops, dealer or otherwise, want you to be happy with their work.
Bosch Master, ASE Master, L1
33 years MB technician