Vodacom cancellations - having no assistance with cancellations! Unhappy client

Problems relationg a Vodacom contract

I have requested for my Vodacom contract to go on pay as you go in November 2020, they said it will be cancelled on 01 December 2020, my debit order still went off. When I phoned today, they said it is not cancelled, and I must first pay my installment for end January 2020, before I can cancel my contract. How can you force a person to continue with your contract, if I have cancelled it, and the contract expired last year July 20 already. Not very professional.