I feel for your loss.
It sounds like you might have frame damage there if the door wont open, but only a shop will be able to tell.
Its hard to say if you can get it fixed for the price you mentioned.
I would not only check with the mb dealer for repairs, I would try other body shops that your insurance allows. I would also check for parts here on the site, or you can try www.silverstarrecycling.com
for used parts.
Is the accident considered your fault?
I wish you the best of luck with getting your car back to the way it was for a good price.