don't let them take the car to one of the garages for starters

then remove anything that you haven't declared

then wait for the cheque to arrive

there may be some haggling inbetween the cheque being written for the ammount you want and it appearing through your letter box

been there, done that, plenty of times, but it does also depend on how bad it's been bent as they may want a scraped car document from you after you've had the vehicle dismantled before they send you some money