I advised a mate to cover the seat backs with some fablon before his kids did something similar... did he listen? did he f........
He ended up taking the shells off and had them painted to match the original finish, cant tell the difference now, just look immaculate like there were never any kids in the back.
Might be the way to go if they are real bad???
I'll ask him how he got the backs off again as he said at the time they were a bit of a pain!