Contract upgrade

I am so furious with vodacom. Not only have they increased their data prices in March they have also kindly decided to do away with certain packages so just upgrade your package and increase your payments with NO NOTIFICATION at all. NO discission with me or offerinh of something else. NOW EXCUSE ME I signed a 24 .month contract for a set contract which is supposed to be legally binding. BUT VODACOM it seems can just change it. BUT let me try and cancel it and I will have to pay. ITS NOT RIGHT