I want my money back

I’ve sent money by mistake to the FNB account on Thursday last week from my standard bank account. I was told to log a call with standard bank to report it. Today I received a message saying they can’t refund me because that person I sent the money to his account was in arrears, we are talking about a wipping R7000. Fnb I dd report that the money was sent by mistake why am I not getting my refund because the person told me that he won’t pay for that money as it was not his problem that u guys took the money. I want my money back I can’t be paying for others people’s credit.