TOYOTA SIENNA 2004 LIFTGATE SLIPPED DOWN AND HIT CAR OWNER IN THE HEAD WHILE UNLOADING GROCERIES FROM TRUNK. NOW, IT SLIPS DOWN EVERY TIME WE OPEN IT. THIS IS DANGEROUS. CALLED TOYOTA AND THEY TOLD US THERE WAS NOTHING THEY COULD DO ABOUT IT. CONTACTED OUR TOYOTA REPAIR SHOP TO SCHEDULE REPAIR. IS THIS DEFECT STILL UNDER INVESTIGATION? PLEASE INFORM. THANK YOU. *JB