Good luck on you case.That happened to a friend of mine who dropped his car off at a body shop, after leaving the car for a few days he returned to the shop to get something out of it and found it was stolen. Wierd part is that after a week the cops found his car in an alley around the corner from the body shop stripped and blocked.
He had documentation and sued, but still, thats your car ya know? Sorry to hear about it man