It wasn't as easy as that I'm afraid. I was stonewalled by Audi and ended up going through the courts to get a solution.
I won't say for a minute that I too the perfect route to get my resolution, but it did work for me.
The place to start is with these guys
Legal Department
Volkswagen Group United Kingdom
Yeomans Drive
Blakelands
Milton Keynes
MK14 5AN
I wrote to them giving them the chance to re-consider their decision and informing them that I would take it further if neccessary.
This is a good reference for the small claims proccess
Small claims
Good luck & let me know if I can help.