Refusal to cancel data contract

I have 2 month-to-month contracts with cell c. On 22 June 2022,I phoned cell c contract cancellation department, but I was told that my contract was uniliterally changed to a 24 month contract.I was informed that I will have to pay the value of the remainder of the contract as penalty fee.

I want to state to cell c that they must cancel that contract otherwise I will not stop their debit order in my account and I don't care if they take me to credit bureau.I can not allow cell c to exploit me, never