Frustrated

I have been paying my FNB account since December 2019 and until February 2024 not much have changed on the outstanding amount. I requested a statement of the account in February and was told that they have to get the statement from FNB itself. On the 5th of July I recieved a statement with no outstanding amounts and no payment required. As from 25 September I recieved massages and emails that request payment. When talking to she consultants the only response as usual is that the matter wil be escalated to the relevant department and then nothing happens. After a few weeks it starts all over again with messages and emails. How can you not have any outstanding amounts but still must make payments.