The local Audi dealership has not, in my opinion, made a good faith effort to resolve a problem with the fuel gauge in my 2003 A4 that has persisted for more than three months. Is there someone higher up in the Audi chain of command who I should approach with the problem and if so, what would be the most effective method of contacting them (e.g. telephone, e-mail, letter)? Thanks for any advice.