2006 GMC YUKON Power Train Problems

This is the 2nd GMC Yukon with a faulty drivetrain I've acquired in 3 years. Both occasions were directly after the vehicle had professional service done related to the faulty system. The transmissions was fully serviced at reputable repair shops and within a month or 2, without warning, the transmissions started having mechanical issues without DTC being triggered. As well as a 2004 Buick Rendezvous with less than 70k miles on it. The 2001 GMC Yukon suddenly lost reverse and park while driving and imploded the transmission in the process. The 2004 Buick Rendezvous started slipping and ceased to move by it's own power when at operating temperature. The 2006 GMC Yukon Denali stopped shifting gears while on the freeway at 55 mph and systematically lost all moving gears within a day also while at operating temperature.

MY 22 MONTH OLD GRANDSON WAS SITTING IN MY 2006 GMC YUKON PRETENDING TO DRIVE. MY VEHICLE WAS NOT RUNNING THE KEYS WERE IN THE VEHICLE THE RADIO WAS PLAYING, I WAS STANDING 3 FEET FROM THE VEHICLE WITH MY BACK TO IT. I HEARD THE TRANSMISSION SHIFT. I TURNED TO SEE THE VEHICLE ROLLING DOWN THE DRIVEWAY. LUCKILY I HAVE A SHORT DRIVEWAY AND LIVE ON A CUL-DE-SAC. BY THE TIME I CAUGHT THE VEHICLE AND PUSHED THE E BRAKE TO STOP IT I WAS AT THE END OF MY DRIVE WAY. I THOUGHT I HAD TO PUT MY FOOT ON THE BRAKE TO TAKE THE VEHICLE OUT OF PARK AND INTO GEAR OR NEUTRAL. WHICH IS TRUE UNLESS THE KEY IS PUT INTO ACC MODE. I BROUGHT THIS TO THE DEALER AND THE SERVICE WRITER AND GM CERTIFIED MECHANIC DIDN'T KNOW THAT IF A VEHICLES KEY WAS IN...