I had a Chevrolet pick-up truck several years ago that had some problems, the dealer I purchased it from was unco-operative about fixing them. There used to be a step by step process outlined in the back of the owner's manual along with a toll free phone number to call. I called and they made an appointment at my convinience at another dealer, they were very co-operative about repairing the problem. I would try working with GM before resorting to consumer advocates or attorneys. Get names and titles of everyone you talk to and document everything. If you don't get satisfaction ask to speak to a supervisor, be polite yet firm. Good luck.