Bad Service on my refund

Hi

on the 25th of February 2021 when i was settling my loan account i made a double payment. i called FNB and asked them to transfer that extra payment to my Wesbank account, they told me won't be able to that as they can only refund the account where payment was made from and they asked for my bank statement so they can credit that account of which i did. i called now and was told that money was paid to FNB Cheque account and i didn't authorise that. my question how did they manage to make that refund to FNB cheque wheres i was told they can't credit diferent account when i wanted them to credit Wesbank