Discovery Bank refuses to cancel credit card

On 30 May 2020, I paid off my credit card and closed it by - phone - email - on the website

Discovery did not close it. In June, I received a statement with my monthly costs. I called again and asked them to cancel and I will not pay the fees.

Still not canceled.

July: another statement. I am fed up with Discovery and their blatent disregard of their client's wishes. I'm at my wits end. How do you cancel your credit card?