Well, I've never had the experience with a lemon, but I would second getting a copy of your state's lemon laws. Spend a day or so to go over it, and then call GM's Customer Assistance. They're the ones to talk to, I suppose. Document who you talk to, and what was said.
Just remember that the representative on the other end won't be able to do a buyback on their own, they just answer phones. From what I understand, it has to get kicked up the chain of command. I used to work in the tech support field, and I know that us schmucks on the other end of the phone can't do sh*t without at least 3 managers, a VP and the VP's dog saying OK.
Now, deep breaths, wax on, wax off, drtyfn-san. Do what you gotta do, and I hope it works out OK for ya.
Corvette= "The ability to pass with class"