Vodacom breaching contract

Considering to cancel my contract with Vodacom. They just raised the fees on my signed contract without giving notice thereof and when I spoke to the customer services the only answer I got was read your terms and conditions. How is that protecting me as a consumer and as a customer. So Vodacom can raise the fees without breaching of contract. And they have no proof of any correspondence that was sent to me informing me of the price increase. So why do I need to sign a 2 year contract and keep my end of the terms but they can change it as they please and I just need to pay. This feels like ***** and a money making scheme. Alteration of a contract to me is breaching of contract. Full stop.