Natan uses his Rav as an agent to sell his chametz before Pesach. The rav sells the chametz to Jose.
On the 1st day of Hol Hamo'ed, Jingram stops by Natan's home and says that he is really hungry and needy and has no food for his family. Natan says, "I have a lot of stuff in my basement. The problem is that Jose owns it, so you have to ask him if he will sell it to you."
Jingram goes to Jose, and Jose says to Jingram, "I will give you the chametz for now, since you don't have money, but you need to pay me for this when you are able."
I assume that there is no problem with Jose selling Natan's chametz to whomever he wants even without notifying the rav, as Jose owns it and can do what he wants with it.
Pesach is over, and the rav buys the chametz back from Jose, and pays him back the amount for all the Chametz. Problem is that Natan's chametz was given to Jingram, and Jose should be paying that part back to the rav.
Jose tells the rav that he gave Natan's chametz to Jingram and Jingram hasn't paid him back. Jose is short on cash, too, so he can't pay back the rav that part either.
Now that Pesach is over, can Natan use his chametz if it hasn't technically been bought back? Can the rav excuse the debt completely or "postpone" the debt saying, "I'll deal with Jingram separately and he can pay me when he is able." Would that scenario allow Natan to eat his chametz?