Personal Loan nightmare

I took a personal loan about 2 years ago. The total amount borrowed to me was R11197 which of course includes interest etc.

I paid every month over the last 24 months not missing one payment. My monthly repayment amount was R751,51. My last installment equalled to R450. When I logged on to FNB that amount changed to R635. I figured that amount included interest etc and budgeted to pay at least R645 as a final payment to close my Personal loan account.

The debit order amount collected today was R754!! How on earth is that possible and yet the personal loan account is still not closed. I’m not happy with the amount collected as that was not stipulated on my invoice and I’m not sure where FNB got that amount from as I don’t owe any extra charges etc. I budget strictly especially during these times but FNB just takes with no explanation.

Even with interest and closing amounts etc etc there’s no way a final amount of R450 changes to R754???