Well, I had a little issue as well with that same Dealership last week. I was going to just take it beccause it wasn't a significant amount of money but if we're airing grievances, here goes.
So, they replaced my whole rear diff assembly. About 8 days later my Locking Diff light started blinking and the Service 4wd message came on the DIC.
Took in here in Austin. Diagnosis - they had forgotten to connect a sensor of some kind at the rear diff. Charge ~50 bucks.
I send the invoice to San Antonio. They say cool, we'll handle it. The next day I get a call saying, "Oh wait, your warranty only covers $40 toward towing. Your bill was $120 because they had to use a flatbed (which they didn't)."
So I actually owe them money now.
His solution, we'll call it even. I say fair enough, it was only $50 but I was not pleased with the way it was handled.
I have a GM extended warranty. My deductable is $200 per major incident. Is it true they only cover $40 toward towing?