Contract being extended without my permission, with the matter not being resolved

Good evening, I had taken 2 contracts with Cell C from January 2020 until October 2021. At about October of 2021 I received a phone call from Cell C telling me that my contract would be extended until January 2022, and that the price I had been paying would be reduced from October 2021 until January 2022. I had even called Cell C to confirm that my contract would be ending. Cell C continued the debit order after the contract ended, I then started reversing the payments in April and May of 2022 and June which resulted in me being added to a credit bureau. I had called Cell C multiple times to try and resolve the issue and would be given little to no help. Eventually after receiving some help, I was told that I had extended the contract which I did not do. They told me that they would investigate the matter and give me an answer within 78 hours which they still have not done. They continued the debit order again last month. When I tell them that I want to cancel the contract that I had apparently extended, they tell me that they cannot do so and do not give me a valid reason as to why they cannot cancel the contract.