No one can fix my ADSL line

I have had my ADSL line with Telkom for almost 3 months now. In the beginning, everything was fine and I was getting speeds above what was advertised. Then our line went out for about a week in September(supposedly ****** cables). I logged a fault and they "fixed" it after three days. Since then, our line is almost unusable. The latency jumps to ~1000 a lot and then comes down to about ~200 after about an hour. The download speed is also less than half than what we're paying for. This makes it unusable, as I use my laptop to remotely access my desktop at work. We have logged about 5 or 6 faults, and each time they tell us it is something different, but they never seem to fix it. I have called Telkom numerous times, and after a lengthy wait time, they just reset the port(which helps for about 30 minutes) or log another fault, neither of which solves the problem. I am rather fed up now, as this is affecting my productivity.

I rated two stars because the service was extremely good for a short while, when we just got the line.