Wrongly listed to Credit Bureau

Being a loyal customer, I paid my contract upfront to amount of R13,200 back in July 2016 and currently left with the credit balance of R-5976.48. Vodacom listed me under credit bureau as if I am owing them R-5976.48. It also shows that it is my monthly installment. I have logged so many calls with them to clear my name. They said I must wait for 21 days that has passed already. They claim to have logged a call with XDS but the reference number does not exist at XDS. Consultants keep telling me that there is nothing they can do and I must just wait. Why must I wait for more than 21 days when this is not my fault? I sent them all the proof that they want via an email to their legal department. All I want is my name to be cleared.