Cancellation of paid up credit card a problem

Discovery card -ref *** Cancelling a credit card I no longer afford is a hussle.Cancelled on the 4 June 2020, got a call back on the 10 June and resubmitted a closure form on 11 June, 14 June and 23 June. They keep on saying they have not received my closure form I have a read receipt and an automated email with a new reference is send to me. Resubmitted the closure form again new reference ***. I called multiple of times all I get is we can’t see closure form , there is no escalation procedure to escalate the matter all they say is resubmit again