Uncancelled contract

Hi, my name is Zanele. I took a contract of 24months with cell c in 2019. The contract was to end last year 2021 which i called them to inform them that i would not be renewing it. They said i should wait for the month which it is to lapse which i did hence i called them in November to confirm the non renewal. To my suprise in December a debit went through from my account which was more than the normal amount. I let it be as I believed it would be the last time they do debit. I am now finding out through my credit checks that the account is still active and it is flagging missed payments for me. I called them on saturday the 2nd July and the consultant just said the account now shows to be prepaid but still went on to say im owing R200 which is said to be a cancellation which i was never told about. On my clear score it shows a balance of R400 something. I never got any help from the consultant apparently there is nothing he can do, i need help, this is affecting my credit record so bad.