I agree a group letter would help.
I think sending it to the UK MD and copying VW Germany is the way forward. 
....No, do it the other way around - VW Germany are 'senior' to VW UK so send the original to Germany.
Well that your opinion and I will put your reply down to one of those that can just be taken out of the context that perhaps you meant

I believe that as the original "limited edition" concept of 1500 vehicles for the UK market is a VW UK statement and that as all of the promises of plaques have also come from VW UK, we should in the first instance direct this to the UK senior management as we have failed to receive a satisfactory resolution from the customer services dept.
Jumping the change of command doesn't always get the right or quickest resolution to a problem.
