Radio/tape Cd Player problems of the 2006 Buick Rendezvous

The contact owns a 2006 Buick Rendezvous. The contact stated that he left his wife in the vehicle while he entered the store. He left the radio on, but when his wife turned it off, the vehicle rolled backwards and crashed into an unoccupied vehicle. There were no injuries. The dealer has not been notified of the failure and the contact has not inquired about this failure occurring with other vehicles. The VIN was unknown. The current mileage was 28,100 and failure mileage was 28,000.