Telkom bills without delivering the service

I pay on average R600 per month to Telkom. For this they are supposed to give me an uninterrupted ADSL internet connection. However, since April this year I have had very intermittent service. I have logged numerous faults and a stream of pleasant technicians have been here, trying to sort out the problem, all to no avail. It seems the Telkom's system is oversubscribed and can't cope. I find it highly immoral that I am being charged for something that Telkom cannot deliver and extremely dishonest that they will not admit that this is the case and upgrade the system as required.