Brakes Failed problems of the 2015 GMC Sierra

Yesterday afternoon while backing out of parking spot, my brakes became unresponsive. The pedal was extremely hard to press and would not stop the vehicle. The result was the vehicle rolling down an inclined parking lot and hitting another vehicle. Normal braking had resumed when leaving the accident. This is the second time for the brakes to become unresponsive at low speeds. Approximately 1 month ago the same situation happened driving through a parking lot. Brakes became extremely firm and unable to stop the vehicle. No damage resulted from that incident. After reading several message boards, it appears to be a widespread issue with this vehicle that results in replacement of multiple power braking components. I currently feel extremely fortunate that my brakes did not fail 5 minutes earlier while picking up my child from school.

Brakes failed. I was backing into my garage and the pedal became really hard to push. I almost did not get stopped before I hit the wall.