FNB bad customer service

I must say, the worst customer service I've ever had. After calling FNB and being redirected twice, I ended up right where I started with no one who could help.

I'm paying off an old personal loan at FNB and when I received the statement today, the total amount have increased from a 20K loan, standing at 38K at the moment which mean the debit orders they collect every month is nit reflecting on the balance. Can someone please answer me this?