Cell C data contract

I had a data contract with Cell C which expired end of February 2022. A consultant phoned me to ask if I want to renew my contract and I said NO as we have fibre internet now. On 15 March the debit order of cancellation fee went off. Thereafter every month the debit order still goes off with different amounts then I must go to my bank to reverse the transaction. The amounts is not even what I paid for my contract it is more and varies each month so I can't block the debit order. I did not give them permission for a renewed contract. I tried a few times to phone cancellations but the call drops or the consultant will put down the phone in my ear after explaining the situation. We phoned to speak to a team leader they took my number and till this day didn't phone me back. Still battling to reach them.