MTN Contract

I had a contract with MTN for 3 years and it ended January 2022. Before the end of the contract I went to MTN Meyerton to cancel. They told me they can't help me I had to call 135 to cancel. I didn't have mtn phone to call, so I sent an email to cancel my contract. I called on the 14th of February and was holding for 23 min, I told the lady that I wanted to cancel the contract and she told me that I can stilll use the number for prepaid and I agreed. Today when I called MTN to cancel my second contract which is suppose to end April, they told me that I'm still using the number that I canceled and they are debiting me R209. It seems as the contract was renewed without me knowing about it. I want MTN to cancel and refund me my money. I don't want any contract with you, your service is poor. Why do you force customers to continue with contracts even after getting an instruction to cancel the contract.