Tailgate problems of the 2011 Chevrolet Suburban

2011 Chevrolet Suburban 1500. Consumer states when the tailgate is commanded to lift it raises between 20% and 50% and then returns to the bottom and locks without stopping the consumer stated when he arrived at the dealer, the tailgate lifted approximately 80% and then without warning an explosive noise occurred and a violent downward motion caused it to close and lock. The consumer went to another dealer and the tailgate opened fully and then closed and locked without command. The consumer stated he has been to the dealer six times for the faulty operation of the tailgate.