Tellkom ruining lives

Telkom is a disgrace, after billing a sim card to my name that I never ordered nor used and fighting for 4 months via various channels and after Telkom confirmed that the line has been cancelled and that there is no outstanding dues, I start getting 10 calls per day from NuDebt Credit Management telling me that I was handed over. Also after checking my credit report, Telkom listed a default in June, 2 months after they confirmed that it was sorted out, This is the reason my home loan application was declined. Where is the accountability on Telkom's side?