You would have to take it to either a Hummer dealer, or a dealer GM authorizes to work on Hummers. You can go to the
HUMMER | Luxury SUVs, Trucks, & SUTs website, and enter your zip to direct you to an authorized dealership. Since you're out of warranty, I don't know if you'd be covered. Possibly, since there was a GM service bulletin. But....since you've got 65k mi., they might just say you were due for brake service anyway. I actually had mine done twice. Once a year and a half ago at 9k mi., and just 2 weeks ago at 18k mi.