Contract Cancelation

We had a cellphone contract for years with MTN and subsequently decided to cancel when the contract was over. This where this particular problem starts. In April 2023 we called the customer care department of MTN to cancel said contract. On the regular debit date they debited an amount of R328 which we assumed was perhaps a cancelation fee of sorts as it is usually stated that it takes 30 days to cancel, so it seemed reasonable as the amount that was being debited prior was a little over R1000. MTN continued to debited for 3 more months so we proceeded to call the customer care again in August 2023 to cancel, and again MTN debitted this month so we decided to go to the MTN at the Grove mall in Pretoria where a lady by the name of Itumeleng informs us we can at cancel a contract at a branch and have to call the call center. We explain that we have called the call center and still hasn't been sorted, and she proceeds to tell us she can't help us, so I suggest we call the call center and she says we can only call from Monday to Friday, so we ask where we can lodge a complaint and she proceeds to say she can't help us with that either. So we ask to speak to her supervisor to which she responds she is the supervisor, to which we ask who she reports to, to which she says he is only in on Monday to Friday. What I don't seem to understand is that one cant cancel a contract where it was opened, one can't lodge a complaint, and made an unnecessary trip to the mall