Billed for products I didn't request for

I signed a cell phone contract for a R250 per month. I the contract I specified that I want only what is included in this R250 per month package and limited the allowed debit order to R250 per month. The first month I was billed R972, I logged a complaint and after more than a month the matter is still unresolved. I received my second bill for over R600. Telkom admitted that it is a mistake on their side, they ad data bundles I do not want, need, use or can afford. I am very unhappy with the service I received so far. I have called the call centre around 20 times and visited the telkom shop various times regarding this issue and when I do visit the office they just put me on the telephone to the same call centre I can call from home. I don't know what to do anymore, I really feel exploited and treated unfairly.