Lets get something straight.
The OP had NO OBLIGATION to allow the dealer to fix the car. None. Period.
As soon as the car came to a halt after impact, the dealer had an obligation to inform the owner of the 'loss' or 'event' or whatever. And ask what the owner wanted to do next
The OP gave the car to the dealer to do one thing and that was service the car.... the dealer has no further authority nor right.
People seem to miss this fact- seem to be blaming the OP for taking it elsewhere.
The concept of "you should have worked with us and let us fix it" is BS.
tturedraider- If you valet parked your car and they crashed it, would you let them fix it? WHY NOT? Shouldn't you be reasonable and work with the dealer???? Just because they are a bmw dealer does not change this fact that the OP had no obligation to allow them to do a thing. You (and others) seem to be making a BIG deal of this, and it has no legal foundation.