DSL Line and phone continually out of order

My phone and DSL line has been out of order for a long time. Telkom say they have fixed it and then close calls, but it stays a problem. This has been so since it was installed. I have another line from another exchange in the house and that one gives no problem. In the few months since it has been installed, it has probably been out of order for about 2 months. But the accounts keep coming even though I cannot use it. I work from home and this impacts on my livelihood. And of course it is impossible to get hold of anyone, or get any follow up.