2002 GMC Envoy transmission problems

My vehicle rolled backwards down a hill and crashed into a waterfountain and a tree in my front yard. Backing out of my garage I stopped quickly after just exiting my garage on a slope of about 6% grade. I had spilled coffee, I put the vehicle into park and stepped out when the car abruptly rolled backward. Both of my children were strapped in their seats and I tried to leap back across the drivers seat with my legs hanging out the door. We traveled 50 feet before hitting the waterfountain and tree.

The contact owns a 2002 GMC Envoy. The contact stated that while driving at an undisclosed speed, the vehicle was shaking. Upon inspection, the contact noticed that the rear subframe had fractured and detached. The vehicle was taken to an independent mechanic who diagnosed that the subframe needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure and advised the contact to file a complaint with the NHTSA. The failure mileage was approximately 150,000.