EFT needs to be reversed

I have a negative balance in my cheque account, which i am paying back every month after closing the account. Someone made an EFT payment of R 700.00 into this cheque account which was not suppose to come to me. He wants it to be reversed but FNB says no authoriry to debit but it is his money. I am trying to phone the recovery department but with NO assistance! Please help me so that the money can be recalled back to the person as he needs the money.