Vodacom ****** and *******

I have a dispute with Vodacom, I signed a contract of R797 and now they've hiked the monthly premium of the contract to R846 and they never even consulted me. I told them when I took the contract that I want a topup and I can only afford something less than R800, now they've hiked the price and when I enquire they tell me about terms and conditions that were not explained to me initially when I sign up for the contract. Vodacom is a ***** that is milking us dry, even the data from vodacom doesn't last. I find it odd because they will say your phone us the one that consume data but when you put a son card from MTN for an example to use on the same phone the data is not consumed. I'm just waiting for my contract to expire I won't renew it and im not going to pay for what I've not sign up for, I want my money back.