complaint

I enrolled with intec in 2007 for marketing management, I got introduction book via post. No instructions whatsoever as to what to do. I paid an amount of r500 a month and just never received any books afterwards for assignments etc. After a year or more i went to the head office in cape town to complaint as they requesting money from me every month. I was told that I first should send through assignments and then they will send books. How can i pay for stuff bi don't get? Few years later cart blanch exposed them for the same complaint and how pupils just never hot the study material. Intec is harassing me by calling me every 2-3years then they stop after explaining to them and then they continue again after 2-3years. I font know what to do anymore.... They have the poorest service ever from the start. What legal processes can I follow as I need to get this over and done with.