Ongoing struggle Discovery Card Cancellation

I have had my Discovery card for a while now...and always managed it responsibly.. i have cleared my account balance to R0 somewhere in December 2019 with the intentions to cancel the card. I have phoned them 3rd of January requesting to cancel..and new charges was added already. Something like R174. The closure documents was sent to me..and i have returned the documents on the same day. That was on the 10th of January. Without hearing from them.. i thought that they will advise once closed. After no feedback.. i phoned again on the 21st of January. They have stated that they have not received any documents from me.. but they might be able to revert the charges backdated to end January. I have again forwarded the original email including the cancellation document to them so that they can see the date on when i requested the account to be closed. No feedback from them again. After forgetting about the issue.. i have again phoned today (13 Mei) asking them about it. Again, I was told that no documents was received..and I will be liable for recurring fees to my account which is over R110 per month. I was also told to try and send a test email to someone with the documents..so.. i did.. all working perfectly. I Have not received any reference responds email from them probably indicating that something is not working on their side. I have used ***. They have confirmed that the email is correct. Apparently there is no other email address to forward the document to.. so.. i guess it is just gonna go on like this.. Today's call was also a total waste of effort and time. What now?