Credit Card not closed after a request to close it

Good day,<br> <br> I have received a monthly statement from Nedbank stating that there is an outstanding amount of R234.22. I had requested Nedbank to close the Credit Card after I have paid it off but seems like they are making money out of people as they keep charging them even when they have requested them to lclose the account. I need explainations, why wasnt my account closed and what kind of service is this to a loyal client who never even missed one payment.