FNB Home Loan charges interest on admin fee

I paid up both FNB home loans on 6 June 2017 and should only have paid the admin fee monthly thereafter, however, I was charged interest on the admin fee. When I lodged a complaint with FNB in July 2017 I was told that this was a "systems error" and that it had been fixed and I would in future only be charged the admin fee. For more than a year this was the case, however, out of the blue in Sept 2018 I was again charged interest on the admin fee. When I again lodged a complaint, I was told that I would not be refunded the interest charged because that is how the system is: the system charges the admin fee in arrears and this attracts interest.

How many people are being ********** by FNB home loans by this **** ???? Others with home loans - take note!!!!

I refuse to pay interest on an admin fee and NIL balance and am lodging a complaint with the Bank Services ombudsman!