FNB Personal loan double deducted

My FNB personal loan for January was double deducted from both my FNB account and my Nedbank account.

On 30 December, I contacted FNB and advised that my debit has not gone off, and asked why the debit has not gone off, and was advised that it would go off the next day on the 31st.

I checked my Nedbank account on the 31st again and it still did not go off, I also logged into my FNB account and it did not go off there either. I contacted the bank through the chat again, and was advised that it would go off my FNB account, and going forward it would go off this account in the future. I raised the concern here that I did not want to be double deducted from my Nedbank account now and received assurance that it would be from the FNB account.

Then I received notification from FNB that the amount went off my bank account, and after midnight received another notification from Nedbank saying the deduction occurred there as well.

Obviously this is an extreme inconvenience to me, as I made funds available in my FNB account even though the mandate was with my Nedbank account, and now i've been debited twice.

I would like one of the payments to be returned to me as a matter of urgency, and I would like confirmation on where the funds would be deducted from in the future (from which bank). Unfortunately it seems like every December this happens, and with school around the corner, I cannot afford to be out of pocket due to being double deducted.

I've been chatting now to consultants for over 30 minutes and have not received even a wink of guidance or assistance on how this can be corrected so far. Got transferred to collections and that person left the chat immediately and now i'm back in the queue.