NHTSA Complaint #11486057 — 2017 TESLA MODEL S

The issue occurred twice over the period of the past two months, both times I was driving on highway with Tesla autopilot enabled ( It is Adaptive Cruise Control), for no apparent reason the car hit the brakes, all vehicles driving behind me had to hit brakes or change lanes to avoid Collision. Both times I created service request with tesla and got no clear answer to why its happening, first time I was told it is because the exit on map was about couple miles from car location so car had to hit brake hard and change lane to make it to exit but car never tried to change lane, it just did hard braking. 2nd time I was told it happened due to wheel alignment not being accurate. After wheel alignment was done I reached out to tesla again but so far they can not confirm or deny if tesla autopilot is safe for me to drive. I was told to use autopilot at my own discretion. Are car manufactures allowed to sell hardware or software without taking responsibility for its safety ?