Cancelled but they keep billing and use NU debt to collect money from unsuspecting victims.

I cancelled my telkom service and they removed the switchboard, months after they kept billing, I kept confirming the cancellation and that the business was closed down. I was handed over to nudebt and they took default against me, I asked for my original deposit back and kept confirming the date the business was closed, months after that date they kept billing. As I have the telkom default , I cannot get a home loan and now have no where to live, I have never rented but rental agents will probably also see this as a bad payer. When I call in to resolve the matter, they transfer me from person to person and no one ever helps or calls back. Total ****