failure of rear hatch

tried to open the back hatch to put something in. When the hatch was almost open it jerks (which gave me warning that something was wrong) and then proceeded to freefall (no restraint at all) on top of my head. I was left dazed, disoriented and in pain...very painful! Continued to open and close the hatch to see if it would continue to malfunction (staying clear of course). It did not correct and now it definitely needs to be taken in for repairs. Can't imagine what would have happened if a child had been the one to try to open the hatch. They would have been seriously hurt! There was an issue when the vehicle was still under warranty with the button that opens the hatch failing to open it and having to be replaced also. There needs to be something done about this! VERY DANGEROUS!!