I've got a 2019 Chevy 2500 duramax & allison trans.
Got 75K on it and never had a minutes trouble with anything......knock on wood!
Pull a trailer with a tractor and attachments, boat and 30ft camper.
I'll say this, if that's a picture of his old rotor that came off beside a new one and an old pad next to a new one then he absolutely needed rotors, pads and most likely calipers too.
first thing I would do is sit in the seat and with your foot on the brake, put it i drive then make sure its in "park"all the way. Might just solve your problem.