I think that is crap.
Your dad sold hillbillies truck.
Hillbilly is out his miney until your dad is able to square with him?
Does this seem right to you?
I understand he made payments for the truck. either give him a truck that he agrees to or give him all of his money back.
That is like you paying me over time for something and when paid off I say I dont have that anymore vut since you made payments to me I will make them to you until paid off.
Does that seem right? Fuck no! you want your money right then and there.
Do you understand? Or are you so embarrassed by the situation and being called out on it for your involvement (as little as it may be) that your blinded by the right thing to do?