FNB Double-Debits My Personal Loan

It has come to my attention that FNB is double-debiting my payment for a personal loan several times a month. And that is appears that the amount taken from my account doesn't always reflect on the amount owed. Another words FNB is taking money from me (more money than the agreed upoun amount) and my loan isn't shrinking.

The last time they debited my account on Feb 27th and then again on March 2nd. And I believe that they may have double-debited my account before in regards to this loan.

Sadly, I was just given the run-around by the Secure Chat. First they claimed that my debit today hadn't shown up on the account (and then would only show up in 48 hours) and then that it had but not the debit on the 27th. I was given conflicting information.

I was told that I can only be refunded was the debited amount reflects on the loan amount. But the debited amount does not appear to reflect on the loan. So what am I meant to do, FNB? Just ignore the extra money taken from my account?

It seems that I am regularly double-debited by FNB for this loan. And that only one of the monthly debits shows up on the loan amount. So where is the other unauthorized debit going?

I expect this to be resolved quickly, especially if it is an ongoing issue.