TELKOM BLACKLISTED ME AND IT WASN'T EVEN MY FAULT!

I cancelled my home line with Telkom in November 2017. They continued to bill me, even though they acknowledge that the line was cancelled. Then they credited the amount that was incorrectly billed to me, barring R2400, which is not due by me as this was charges after November 2017 they did not reverse. They handed me over, I cannot get student loans for my children now. I logged my issue with them on 31st December 2018, I was told that they would sort the problem out in 7 - 14 days. It still hasn't been done. I have phoned and phoned. I have tracked it on the complaints tracker and it hasn't even reached the dispute department yet! Each time I call, I get told the matter has been escalated. A guy by the name of Donald is supposed to be working on the matter and he was supposed to call me back 3x already and I am still waiting. I was blacklisted for something that is not my fault and they won't even just give me a letter to say the error is on their side! I don't know what else to do! I need to apply for a student loan for my children and Telkom are aware of this and still no help from anyone! They don't even answer emails!!!