Nedbank debited me a month after i paid up settlement for credit card and closed account.

I cancelled my credit card more than a month ago and paid up my settlement balance. However, a month later a debit order still went off. I have gone to two different Nedbank branches to ask for my refund and I was promised that i would get it in 7 days. I have even called the legal section of Nedbank twice and I was told to email my bank statement but up to today no refund has been paid into my account!