FNB - how many more mafia tactics do I have to expect?

I requested a statement from Groenewald Lubbe regarding my FNB Chq account they were managing since 2019. It alarmed me to see FNB add an adjustment amount of R20,000.00 to the debt. I immediately contacted Groenewald Lubbe and mentioned the induplum rule where the interest cannot exceed the principal debt. By this time I had paid almost R20,000.00 . FNB failed to let Groenewald Lubbe know that the R16,000.00 handover amount exceeded the principal debt.

So there was a balance of about R13,000.00 which legally should have been R3,000.00. Even though FNB acknowledged the induplum amount via email, I did not pursue it as Groenewald Lubbe, representing FNB made a full and final settlement offer of just over two thousand rand. I made the payment early last year and received the confirmation of account settled and closed. Today by accident I happen to hear by FNB that R10,000.00 is still owing on the account. This matter is legally settled. No one has asked for the money even now.

How does FNB and Groenewald Lubbe conduct business?

This is certainly not professional and should be brought to the banking ombudsman and law society for integrity and unprofessional conduct. Which I plan to do.

This is about the 5th time FNB is asking for money I have aready paid. After I provide proof I receive a generic apology letter.