EAL, here are the steps I would take:
1) Contact an attorney.
2) Demand to see your car so you and your insurance company's rep can inspect the damage.
3) If you are dissatisfied with the bodyshop where the dealer sent your car have your car transported to a bodyshop of your choice.
4) Insist that the bodyshop use all new OEM parts.
5) Demand the dealer give you a loaner MB vehicle until your car is repaired to your satisfaction.
6) Look for another MB dealer to work on your car in the future.

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Fred Hoelzle