Welcome to the forum. Without knowing what brand toy hauler you have, any answers will have to be very vague.
Can you check the rollers to make sure they are aligned properly? If they are out, the cables can jump off them, and start grinding away at the frame.
If the dealer can't fix it, you may have to re-engineer your bed so it will keep working for you. Heavier-duty rollers and additional bracing may be the way you will have to go.
Two wrongs don't make a right, but three rights make a left.