Clearing of bad debt letter from Telkom. They've owned me money and not the other way around.

For 6 month's I've tried to cancel my line rental at my old address and for 3 month's I've tried to get a credit of R1561. In other words Telkom owed me money. I've discovered 3 week'a ago they've reported me to Transunion for bad debt!!! I really don't get this. They owed me money and they reported me for me for bad debt. I'm now in week 3 trying to get a clearance letter from Telkom to send it to Transunion to clear my name. They've also told me 3 week's ago I will receive a letter within 72 hours. Still haven't received anything. This result now that I can't apply for a home lone or anything because of what Telkom did. How will I get my name cleared??? Because I don't get any help from Telkom . And the way they've treated me is not fair. Please help!!!