What is happening to Telkom

I have a 4mb line capped, thus no throttling right? I have a MikroTik router so that I can monitor exactly what is happening on my connection i.e(Which Pc/Phone is hogging the internet and how by much). Every day (for the past 6 months at least ) our Internet is unusable from around 5 the afternoon till past almost 10 at night. It has now reached the point where most of the day our Internet is unusable. We have pings over 700 to local points and we reach downloading speeds under a quarter of that of a 4mb line. We have complained over and over and they tell us that its congestion. I don't give a **** if its congestion that means that they are promoting internet speeds that they DO NOT supply and service that they DO NOT supply.