I'm not sure who would be your first port of call.

The Garage you bought the car from or BMW Direct.

To that end, I would send it to both parties. I would also send a copy of the letter to your solicitor if you have one, signed and dated exactly as the other 2 letters.

What you must do is get the pictures printed and sent with all of the letters. And don't hold back with how angry you feel about what happened (or didn't).

Fianlly mate, as you know, I print lots of materials for the countries biggest Law College. One thing I print is something called Statutory Extracts of Law. This basically outlines most laws and gives examples etc. If thing get stuck, talk to me and we can consult this for details / angles.