On or around July 12th 2025 at low speed of 2-4 mph my rear end locked up sending everyone in the vehicle hard stop forward. The vehicle wouldn't disengage leaving me no choice but to have it towed for the second time 1st time happened exactly the same about month and a half prior. Gmc service department department claims they couldn't find anything wrong after it sat for two days in there lot after having it towed they were closed weekends and looked at it that Monday morning finding no signs of anything wrong. After picking up my vehicle I strongly feel like if at higher speeds or even environment this issue will endanger myself passengers and bystanders. I need help with resolving this safety issues asap please. Gmc hasn't been much help service department nor Gm support options.