BILLED MORE

I have a contract with cell C, Im paying R189.00 per month. then it happened this month that they debited R208.00 and since last year they have been debiting R189 the contract i signed with them. I asked the lady I talked to on the phone when I took the contract if I wont be paying anything more than R189.00 she said yes and I asked thrice the same question and she gave me the same answer. Now all of a sudden this month they deduct more money which was R208 and I phoned them complaining they told me that terms and conditions have changed, which I never read or received those terms and conditions and taken from the sales lady's word who sold me the phone now her word has changed the contract is now changing. If Cell C is not fixing this contract Im taking it to the consumer counsil and dont mind taking them to court because its a breach of contract. When they advertise or sell their cellphones they make clients believe that they pay a certain amount while they change what they say in the long run. I feel like I have been de*****ed and the contract has been breached. This is the second time Cell C gives me bad service. I want this fixed or no more Cell C in my life