NHTSA Complaint #11522061 — 2021 GMC TERRAIN

I was backing out of a parking spot when I came in contact with a vehicle going east bound in the parking lot the contact was on the rear right side of my vehicle before I could do anything my vehicle sped up and proceeded to go forward jump a curb I had my foot on the brakes when I realized I wasn’t stopping and heading for a garage I turned right trying to avoid the garage but still hit the corner of garage causing damage then vehicle stopped and shut down.The Vehicle is still being repaired the mechanic said there was damage to a box and cable going to transmission but couldn’t say if it was the fault reported to police end insurance but haven’t gotten any response reported it to General Motors but haven’t gotten a response