I was side swiped a few months ago in my '97 C230. The right front quarter panel as well as the door needed replacement. Nevertheless, my gut instinct was to take the car to a Benz dealership with a body shop to have the work done and I'm glad I did.
A bit of history: When I bought the car, the right passenger door was painted at a non-benz shop (I was told that there was sufficient paint scratches to warrent a re-paint by the dealership where I bought it). I noticed that when closing the right door a sort of rattling noise. Being new to this type of car, I didn't pay much attention to it. When the benz shop worked on the car, the mechannic told me that the door had not been properly reassembled and that non-benz parts were used (hence the noise). The door now closes like a vault - this is because it was properly attended to by an authorized benz body shop.

To make a long story short, if you want the car back to how it was previously, go to a MB body shop and get it done right.