MTN *****ulent deduction

My contract ended in February this year 2024. I received a call from MTN saying that I must renew my contract but I cancelled instead and they said that March would be the last month for deduction as it was already on the Roll. In April they deducted money, as I had cancelled I blocked MTN not to deduct. Then in May they did again with a different reference number to access my account as I had blocked them with a different amount being deducted yet I received no data as much as they were deducting. I called my bank and they said that what they are doing is *******. Today 17 June 2024 I consulted MTN for enquiries and they said that it was blocked instead of cancelled and that I am Owing R400 even though I was not receiving data that you could say I had used therefore I owe MTN. They gave me cancellation letter with reference *** and they said that I should call to officially cancel as the document given to me is not official although it has reference. Kindly assist on this matter as MTN is deducting in my account without my consent.