Gee Webster,
It sounds like you've stepped into a huge pile of Government Motors scat.
The jerks took a bailout from Obama and they still keep using parts made in China and charging retail price for them.
After the ignition switch debacle and all of the denials about people getting killed in their Chinese cars, I don't think I'll ever touch another GM vehicle. My '95 Silverado has turned into a total rust bucket that is being held together by the paint. I guess they started skipping the zinc dip a long time ago in an effort to make enough money to pay the exorbitant salaries of their upper management.
But, mine still runs like a scalded dog because I'm the only one who works on it.
The dealers stopped hiring mechanics in favor of cheaper part replacers. They are kind of forced into that corner because GM charges a dealership through the nose for everything. Most of it mandatory.
The dealers aren't going to cut their bottom line by making warranty repairs they might not get paid for.
If it were me, I'd be talking to a lawyer about your state Lemon Law and get my money back to go buy a Dodge Ram or a Toyota Tacoma..