Cell c ruined my name ***

I have a contract with CellC , for the past few months it wasn't deducted from my account i sent them emails to fix this with no response. Last they have been experiencing challenges with the system now its fixed now when apply for credit they say i have to sort cell c account ,i called cell c to request a letter that is stating that my account in upto date but they told me they cannot help . I want to cancel the contract today. My account had money all the time. Im completely shuttered by this experience. I want my name cleared