Automatic Emergency Braking problems of the 2021 GMC Sierra 2500

I purchased a 2021 GMC denali 2500 in December 2023. A couple days after purchasing the vehicle I received a message on the dash saying the front camera was not working. I took the vehicle into the dealership where they said they reset the computer and nothing was wrong with the vehicle. One month later I was involved in a collision where a vehicle turned in front of my vehicle and the automatic emergency braking failed to activate. I applied the brakes but due to my delayed reaction time 1. 5 seconds, I broadsided the small vehicle with my large truck. Luckily the speed was only 20 mph and no one was hurt or killed. At this time I did not know my vehicle was equipped with aeb. In October I discovered through gm and a different dealership that my vehicle was equipped with automatic emergency braking. I have had several occasions when the aeb including the crash where the aeb should have activated but never did. In 11 months I have never had the aeb activate. I took the vehicle into the dealership where I bought the vehicle and they said their computer said everything was operating correctly. The tech never drove the vehicle where the aeb should have activated. I have driven many cars and even the same model vehicle as mine, so I know what the aeb feels like and my vehicle the aeb is not working. The dealership told me to take the vehicle they checked everything gm told them to check. When I talked to gm they told me to immediately take the truck to the dealership and the dealership did nothing.