NHTSA Complaint #11575650 — 2017 CHEVROLET SILVERADO 1500

In reverse my brakes dont work, its like they are grinding, ive changed the rear brakes hoping to fix the issue, i have no codes. It has almost made me wreck due to failure to stop with my kids in the truck, also the afm system is defective in order to keep my engine as safe as possible i had to put a afm deactivate plug into the obd port. Ive tried to figure out the brakes but no one can explain. Spending 34 thousand dollars i expect to have my vehicle safe for my children. I have been strictly chevy my whole life but this is unacceptable. Where we live in alaska id expect the vehicle to be in order and it does it mainly at steep hills and it hasnt done it when ive had people look at it.