I know this is of no help now, but it may help for the future... Before i let my car in any garage for any work or MOT, i know it sounds geeky but i spend 10 mins on the garage forecourt just taking pictures of the car before it goes in, I.e such as the bonnet, wings, doors, rear qtr wings, hatch ,all bumpers, sideskirts, wheels, mirrors, interior, engine bay, well anything that is prone to being damaged and make sure they see me doing it and making sure that the picture of the garage with the company name is in the photo with the car.. oh and make sure you have a date stamp option on your camera.
Yes i know its a 35mm film everytime it goes in and i know its a pain that you have to take it to a 1 hour processing place that does a date stamp on the back of the printed photo while the car is in the garage but i would rather pay £30 a year on film and processing then paying upto ££££'s in damage that i cant prove was done by me.
Oh and no point using a digital camera cos that wont hold up in a court if it ever got there cos the picture may of been modifyed or the date could be programmed in wrong.