We were two people making payments back to Bank of America on a repo car. I settled with BAC and paid out the requested amount. So I thought. Second person was under bankruptcy sill had payments sent to BOA for the repo car years after I had payoff the settlement amt. Now, no one knows where the overpayment.

Both ask for an accounting ( report of all payments to the account)

Both of you look though payment proof and find and prove you over paid. Ask them for the money refunded for over payment, sue if they will not pay it.