Billing me for a paid up account

I'm very angry right now, I settled my direct axis account in December but they still went and debited my account. The guy I spoke to told me he will log a call and they will refund my money, I then went to the branch to reverse my money. When I called I was told I was supposed to send POP after paying, I then emailed the POP but I'm still getting messages that my account is in arrears. When I called their complaints department they keep on telling me to wait until their finance department allocates the payment. They really messing with my credit profile and irritating me with their collections SMS. Worst experience I have ever received.