You'll have to verify for your exact year, but most later model GM vehicles with keyless entry can be reset easily at home.
With your parking brake set, ignition "ON" (engine off), hold down both lock and unlock on the keyless remote. A few moments later you should hear the vehicle honk. You'll see "SERVICE TIRE MONITOR" or similar pop up on the driver info center. Immediately hop out of the vehicle and start letting a few PSI out of the front tire. Don't go crazy, you only need about 5 PSI out in 30 or so seconds. The vehicle should honk to confirm the tire is programmed as the left front. Move to the right front, repeat the same procedure and continue clockwise until you're finished with the driver's side rear tire. To confirm a complete programming, the vehicle will honk twice and will then be out of programming mode.
Your tire pressures will now read in the correct locations as indicated by your driver information center. You'll now need to correct the tire pressures back to the specification inside the driver's side door jamb (as your current pressures are quite low)