Bad Service at Cell C

I opened a data contract telephonically with cell c and activated it hoping that it was what I have signed up for but only to discover later that it was a wrong product which then incurred costs that I was not aware of. I called cell c several times requesting for assistance but unfortunately I was never assisted. I am supposed to be paying R99.00 for my data contract but I was send a bill reflecting an amount of R618.00 which is for an open line that I never requested for. I requested a data usage record since they claimed that it was consumed through internet of which I have never even attempted. They told me that they cannot get hold of the recording for my order but I still have to pay R618.00. The month is ending and I am sitting with a billing that need a huge amount of money I was not expecting and I cannot be assisted.