Why pay for no service?!

I am contracted with Telkom to supply me with a 4mbps ADSL line. For about 2 months I have had intermittent / no connectivity on my line. I have logged SEVERAL faults, and technicians have been dispatched to check the exchange, all without results. Each time I contact the call centre, another fault is logged, and the process starts all over. I am paying my accounts diligently, but receive no service and help from Telkom! This is bordering on breach of contract from Telkom's side, and I want to either be helped and my service restored, or my contract to be voided. How can such a large company disappoint me so much?!