Unable to cancel contract

Telkom is overcharging me for my mobile contract I have with them. I have two LTE mobile deals one of which was due to be renewed this year. When they called me on two occasions I made them aware I would not be renewing my service. For the month right after the contract was due to expire they correctly charged me only for the remaining device. But for the month of May they went back to charging the full amount for both devices. I noticed this months bill again will be charged for both devices. I can’t understand why they are able to effectively renew a contract without my consent. They have caused a financial burden on me as I client without my consent to their service. Today I went on their app to see if I can cancel the request for the third time now and I noticed there is a 30 day notice period. Now given the ********* handling of this issue I would not be surprised to hear now I need to wait this additional time before I can cancel effectively they would have recover three months additional income on a contract that was cancelled. This is ******* which SA mobile providers have been getting away with for many years with no recourse to the consumer. Where is the CPA in that.