Unpleasant service

Gooday, iam writing the review on behalf of my mother she has contract with cell c (Gladys Ngethu) she canceled her contract on the 10th July after numerous agents called her telling her she still owes R1489 my mom disputed the amount as she paid them fully each month. We emailed customer services and called with no help they keep saying they will call back it's been a week now and this is affecting her credit score.