FALSE PRETENSE

On the 2017-10-10 I once again make the mistake to go to Cell C. I ask the sales person I would like the cheapest contract because I do have a work cellphone. He show me a sim contract for only R129 per month where I get 80 call minutes and 100sms, at that stage it was a special for 10gig for 3 months or when it is finish. So accepted sign contract. The pas three months I received bills from over R400, I called customer care where they told me that this contract is an open contract(what ever that means), I then told them that nobody not even the sales person indicated that to me and nowhere on the contract that was stipulated. Show I ask them to cancelled and only deduct R129 . At the shop they informed me that I must contact 140 to add data if I want. I than ask them if I am going to get back my money of the three month and they could not tell. Now I want Cell C what are they going to do about this. I also want to cancelled my contract because there is always an issue. According to me it was false pretense and breach of contract. If I cannot get an satisfied answer from Cell C I have no option to take it further