Refusal to Cancel Contract

I have cancelled my contract over a phonecall on the 20/11/2023 at 15:03, number ***, where my contract was immediately changed to a low premium as advised by the Vodacom consultant. However, I was still debited the the original contract amount of R341 for December 2023 of which I reversed on my bank app. Vodacom is now sending me endless nonsensical smses asking for payment. They are not responding to my emails or just ignoring them. They are actually making it difficult to cancel the contract with them.