False reporting to credit bureaus

I have a cell c fibre to the home contract (which is riddled with its own problems) and pay monthly via EFT. Cell C has registered me as a bad payer on credit bureaus, despite my account never being in arrears. Furthermore, they have incorrectly reported the monthly contract fee by inflating it, thereby creating an impression that I have higher debt. Their billing department has confirmed that my account is not in arrear (but actually in credit!!) and transferred me to the legal department, which never answers its phone. I need them to clear this record as it is proving prejudicial to me. Stay away from this company.