Five months to cancel my account, I am ****ed off

I took an invitation to take Diners Club via Standard bank. A year later without using it once I decided to cancel it. Realised I had raked up about R1700 in service charges. So I paid them and sent proof of payment and asked them to close the account (around August - September). I have since received new invoices, I have called, emailed, screamed and this evening I got yet another invoice with balance of around R330. I am ****ed off and I am not going to pay it. I dare them to blacklist me as I have all the emails and can pull my itemized billing to show I have called them. I am livid! I don't have time to call your call center non stop and get no closure. Send emails and get no closure. I get better service from ****a's shops than from the so called Diners Club International.