Nedbank is useless the want you to keep paying for something you don't need

I am so frustrated I have paid up one of my credit cards and for some reason Nedbank wont close the account even when I send the email address to request the credit card to be closed so I can receive a paid up letter, I am trying to clean my credit record but Nedbank will rather have me pay R 50 rand for a credit card that I no longer have use for