Unauthorized debit order

I have canceled my contract and still being debited for a phone I no longer have. On 30 Aug 2024 I was debited R747.29 and I am unable to revert it with my back, they referred me back to Telkom . Please reverse my funds ASAP. THIS HAPPEND ON PREVUOIS OCASSIONS, I CALLED AND IM TOLD TNE CONTRACT WAS CANCELLED I SHOULD NOT BE DEBITED.