Hatchback/liftgate Support Device problems of the 2013 Chevrolet Equinox

Purchased vehicle approximately June 29, 2019 from chevy dealer in roseville CA. About 3 months after I purchased vehicle I noticed the liftgate coming down by itself. I notified the dealer and set up an appointment to bring vehicle in. In the meantime the check engine light started coming on and staying on, so when I made the appointment I also mentioned this to the service agent. I took the vehicle in , as a drop in appointment because I stay over an hour away from where the vehicle was purchased. I;d happened to be in the area on this day, the vehicle was checked in and the service agent helping me asked could I leave the vehicle I at this time replied no, because of how far we'd traveled to get there I did not have a way home. I'd stated to him at this time when I'd brought the vehicle in before for service that I was provided a courtesy vehicle, he said that would not be possible and that I could rent a vehicle, I declined. The agent came outside to witness the liftgate going down on it's own and again asked if I wanted to leave the vehicle,I again stated to him I drove over 1 hour and I did not have a way to get home. He at this time stated he had 300 vehicles ahead of mine and it would take him some time to get to my vehicle. He was very rude and unprofessional while helping me. I asked to speak to his supervisor which I did and he also witnessed the liftgate going down on its own, we in turn went inside to check the warranty and extended warranty I had on the vehicle, however, I was told it had expired the prior month and did not cover them checking to see why the check engine light was coming on. I believe the dealership sold me an unsafe vehicle and they refuse to try to work something out. Recently, as I was in the rear of the parked vehicle the liftgate came down on my shoulder which required me to seek medical attention.