Hang in there it'll all be good. BTW just call the duty sup and tell em what happened. See if you can get an extension on report date if you really think you'll need one.
But am a bit confused why you have to take accident damage to a dealer. They are just going to outsource it to a body shop most of the time. Not to mention there is a Mercedes dealer in Laredo which is closer to you than San Antonio.
EDIT: Ahh the one in SA has its own body shop.