NHTSA Complaint #11400321 — 2016 GMC SIERRA 1500

I'VE HAD MOVEMENT IN MY DRIVERS SEAT SINCE THE DAY I'VE OWNER THE TRUCK. GMC PUT IN A SHIM KIT TO ADDRESS THE PROBLEM BUT IT'S STILL ACTING UP. THEY REFUSE TO REPLACE OR REPAIR ANY FURTHER. ALSO MY TRANSMISSION HAS A HORRIBLE SHIFTING PROBLEM. WHEN IT'S COLD OUT OR AFTER THE FIRST TIME SHIFTING INTO GEAR AFTER SITTING A LONG TIME, THE TRUCK LAGS TO SHIFT INTO GEAR THEN ALL OF A SUDDEN LUNGES FORWARD OR BACKWARDS DEPENDING ON WHICH GEAR I'M IN. I'VE ALMOST RAN THROUGH MY GARAGE DOOR AND SIDE FENCE AND HAD TO SLAM ON THE BRAKES. GMC HAS LOOKED INTO THE ISSUES BUT WON'T RESOLVE THEM. THE LAST 'REPAIR' MADE WAS TO CHANGE OUT THE TRANSMISSION FLUID. THAT HAD HELPED WITH THE HARD SHIFTING WHILE DRIVING BUT THE TRUCK STILL LUNGES FORWARD OR BACKWARDS AND LAGS SHIFTING INTO GEAR. I'VE HAD TO LEARN TO DEAL WITH IT BUT ANYONE ELSE WHO WOULD DRIVE MY TRUCK COULD SERIOUSLY HURT THEMSELVES OR SOMEONE ELSE