Worst call center agents

On the 20 October 2020 I was told that my FNB account was handed over to them. From that day on they have called me maybe twice a day. When when making arrangements, they still call an ask when will they receive payment. Via email it isn't any better, can easily get 2 emails from them saying the same thing. I then got in contact with them via whatsapp requesting a rebate, they said due to the amount, I do not qualify. This was maybe mid March 2021 when I paid up in full. I have called, emailed and sent a whatsapp, no one assists. The agent on the whatsapp says she will remove my number so I dont receive stalking calls anymore but that's about it. If they don't hang up when your call, they just give extra instructions on things to try for assistance. I am angry, they hound a person to pay what u owe and now that u have they don't care to send a pay up letter or anything.