The contact owns a 2012 Buick Enclave. The contact stated that after pressing the liftgate button to the open the rear liftgate, the liftgate door opened before suddenly falling downward and closing. During the incident the liftgate door had made contact with the owners head. The contact sustained bruised head which did not require medical treatment. The manufacturer was notified of the failure and informed that the VIN was not included in the NHTSA Campaign Number: 15V415000(Structure). The contact indicated that the vehicle had experienced that same failure listed in the recall. The local dealer was not contacted. The failure mileage was 105,000.