Personal Loan

I had a personal loan account at FNB. I settled the full amount the date before the debit order would go off again. On the following day, the debit order still wothdrew money for the personal loan. I emailed the Personal Loans Department of FNB and a refund was made, but by their mistake they made the refund twice. Now, according to FNB, I am liable to pay back the one doubled refund. This is absolutely unacceptable seemingly it was FNB's mistake. I will not pay for FNB's mistake, they are liable for their own mistake. The client service over the phone from the Personal Loans department was pathetic. I will not pay for FNB's mistake that is not part of the contract. I would advice viewers to rather search for a better bank when in need of a loan!