Owners/service Manual problems of the 2017 GMC Acadia

We bought this vehicle in late January 2018. The car was a new 2017 GMC Acadia. We had the car a few days when my wife said that she could not get the horn to work. She said she looked at the manual and found where to push but nothing. I tried and could not get the horn to work either I called to and made an appointment for the dealer service to look at the car. They informed me that it needed a new contact. Told me they would call when the part comes in. I still haven't head from them and called a couple of time and was told again, we'll call as soon as the part comes in. I believe this is a big safety problem as several time we need the horn and could not get it to work.

Power liftgate malfunction- liftgate was operated from the rear switch. Upon activation it rose almost fully and then slammed down on a person while they were accessing the rear cargo area, injuring their nose and face. Liftgate failed to stop at obstruction. From that point on liftgate failed to open or close without manual intervention. Vehicle was stationary, engine running and mostly level street. Weather had been rainy but was not raining at the time, 63 degree temp. Not sure if it was in park or drive, but brakes were applied and other passengers were entering the vehicle. The next morning the power liftgate has operated normally.