Why a contract?

<p>I have a 24 month contract with CellC and today I received my statement and my contract amount of R347.27, has now been increased to R363.26. I spoke to a lady named Vuyo ) who told me they send me an sms that CellC tariff are going to increase (A general sms) and that I should check my contract. So i went and checked my contract and nowhere does it say that they can increase the price with in that 24 months What is the purpose of a contract then, and shouldn't both parties agree to it. Then I called back and spoke to another lady that told me to phone head office and the phone went dead. When I call head office I don't get response. My contract is coming up for renewal and I think to reconsider renewing it. I've been with Vodacom for 14 years before going to CellC and this is my second term contract with them, not once did I ever have an amount increased with in the contract. I'm not happy and will take this further.</p>