Debit Order Charge on Cancelled Account

I came on your platform in April to complain of the bad service. I was being overcharged, and due to Cell c's incompetence I decided to cancel my contract. I was contacted by Skhumbuzo Ndlovo eventually , and he assured me that my account is now sorted . I never got any confirmation in writing to this effect, but I trusted his word. It seems that I was wrong again to do this. Once again a debit order had gone through my account. My cellphone is on Prepaid, so why does Cell C, debit me??? It is such a headache. I can ask my bank to reverse the debit, but all this incurs 'Charges'. Last month and previously it cost me so much in bank charges to reverse all the extra debits, and when I do reverse it, they just send it through again anyway. I need them to STOP DEBITTING me. Obviously Skumbuzo **** to me again. He did not cancel my account !!! He made out like he was doing me a favour to do so, even though I never got my full refund on the previous overcharges as well. ?Please can someone sort my account out once and for all. I intended to get another contract with Cell C as soon as I can decide on a package, but their service is holding me back! I need help with this urgently.