Failure to issue a letter on Incorrect billing

<p>Somebody from MTN decided to upgrade my account without my consent which led to 3 months of incorrect billing. The error was finally fixed but left an incorrect amount on my credit record.Icalled Mtn to request a letter stating the accounts I have with them as well as the monthly installment due. I was then given ref: ********** 46 and was promised that the letter will be sent through in 24 hours from 05 January 2016. After calling so many times, being transferred from one person to the other holding for hours for management until the call ends in your ear I still have no letter and a bad credit record caused by the incompetence of MTN employees </p>