Charging me extra interest even though there is a payment arrangement in place.

I've always been happy with FNB, until now. 35 emails and 4 trips to the SAME FNB BRANCH later to their Loans Department for a payment arrangement on my monthly installment and STILL no communication from their side! Then they still have the ****** cheek to charge me double interest and arrears DESPITE me trying to make an arrangement. ****** pathetic FNB! Maybe I should report you to the NCR.