If the second Dealer has a GM rep coming down to check out the car, that is the best you can hope for. It means the Dealership has hit a brick wall with all they can do and now it is up to Chevy to try to correct it. As long as you have a loner, don't look a gift horse in the mouth.
If the GM rep can't fix the problem, you may very well have a case for a buy back from them, so hang in there and be very polite because they can do more for you at this time then you can do to them if you start to get pushy.
