Horrible Account department

I have been paying my account EFT , as my account was up to date, and they still made me pay R3300.00 last week, they also black listed me for an account that was paid up to date?? I demand they refund me back in cash, I do not want credit on my account, and I want this account closed ASAP !! They have violated my consumer right and destroyed my good credit record, there call center agents have been stalking me, even when I try and explain that I have made payments they get rude and demand I pay. I have sincerely had enough now. I will never ever buy from Ackermans again, and never refer anyone to them