Let's see where to start...

Let's see where to start...
2015 HD 2500 w 58K miles and still under warranty. First time there with intermittent clunking sound from drivetrain and told cannot reproduce, drive it until it breaks without putting it on the rack to make sure no safety concerns. Second time there was 2 wks later w same intermittent clunking sound and now video in hand showing truck failing to move when placed in reverse. Told this time that dealership could not help with loaner/rental as rental company had no gm products. This left me ubering to rental company and spending $270 on a week long rental. Pick truck up 7 days later after transmission housing body had been replaced. Less than 12 hours later (sat morning), truck making intense/loud grinding noise from rearend and still some clunking noises. Took truck back to dealership where one of the mechanics also heard the sound albeit not as loud as earlier. Missed a call monday morning-no message left. I made numerous calls back and finally got ahold of my service adviser later that afternoon. Was told truck was "ready for pickup-couldnt reproduce the sound."

Really?? The failure in making an honest attempt to diagnose the mechanical problem, lack of customer service, and the poor communication from the service team leaves me at a loss for words regarding the incompetency of this dealership's service department. My wife and I both drive GM vehicles purchased new within last 3 years. We'll be trading both of them in when this fiasco is done and will never purchase from GM again.