Struggling to cancel my contract

I requested cancellation quote for my contract at vodacom after they failed to correct my montlhy premium. I have made payment on the 04.12.2020 and have sent through the required documents on the same date but till today my account is still not cancelled. I have been calling to follow up but i am getting different reasons as to why its still not cancelled. Now i have received an invoice showing that they will deduct the premium month end when i enquire today i was told that wether the contract will be cancelled or not i have to pay month end of December.