Charging for money I do not owe.

Cross posted because Pick n Pay is shifting blame and not willing to help me.

I have a clothing account with PnP. I have paid that account diligently since it was opened. I have always paid A LOT MORE than just my installment. But apparently I am not a valued client. PnP wants to milk me for more than what it is their share. The last invoice I received, the balance owing was R921.93. I paid R922.00. A massive 7c more than the outstanding amount, but let's not forget I paid everything (and more).

I get my latest invoice. I owe R47.50 on interest and fees - on a POSITIVE balance mind you because I did not tell reasonably intelligent people that I settled my account. I mean, the account is overpaid. I am slapped with another amount, this time R122.60 to - in their words "settle my account".

Settle WHAT exactly???????????????????????????????????????????? One can only charge interest on OUTSTANDING BALANCES. One can only charge credit protection on OUTSTANDING BALANCES. You have MY MONEY in your books. You owe me and not the other way around. You need to make this right asap.