The Hummer dealership was in an auto group that included Cadillac, but all their service was done in their service dept attached to the Chevy dealership. That's fortunate for me for several reasons - but most important is that the Chevy dealership kept the excellent Hummer mechanic. I'd always recommend Bellevue Chevrolet for Hummer service because of that mechanic. Example, I had my air bag module think the truck had rolled (fortunately no bag deployment), and the guy recommended replacing the module. It was close to $800 to get the part and the repair... once it was done, a day later the light came back on. The mechanic had warned me he found two potential problems - either could cause the problem. When the light came on, he literally took the dash out and re-crimped all the pins and clean the pins so the light wouldn't come on... took him nearly 2 days. Want to know how much I paid? for the problem that wasn't really his? not a red cent.
He doesn't know this, but he's gotten a lot of work because of my recommendation; and rightly so. Also, I pulled the module apart and found the bad resistor (so sue me, I was bored...)