UNFAIR BUSINESS PRACTICE

My debit order got returned because Cell C debited my account BEFORE THE DUE DATE & DID NOT BOTHER TO INFORM ME. After countless backwards & forwards of being told to do a direct payment, been told the debit order would go off I got a call from activations and was told to do a direct payment orherwise my line would be blocked. I WAS ASSURED THE DEBIT ORDER WOULD NOT GO OFF. I did a EFT payment & lo & behold the very same night Cell C debited my account so I paid double! But that wasnt the worst, I demanded a refund but without even asking me Cell C went and allocated the extra payment to the account ONLY DUE ON 25/10/23. Who gives Cell C the right to do this without informing their Clienrs first, it was just done by Cell C & their whole attitude is "Thats how it is". To me that is NOT acceptable, they made the **** up but I had to pay, I didnt budget for a double payment so I am out of pocket. I have a few months left of my contract & will NOT be renewing OR UPGRADING. SO CELL C PLEASE PUT ON RECORD THAT YOU CAN CANCEL MY CONTRACT ON EXPIRY DATE