Can Vodacom increase a 24 month contract.

My 6 contracts with the biggest name in South Africa, VODACOM, is increased with 10 % while the contract is still running and not up for renewal or whatsoever. My question to VODACOM is: why can they increase tarriffs and I cannot lower my contract to fit my pocket? The thing is we all sign the contracts and are happy to leave the shop with the newest phone etc. but never have a look to the small print on the paper. The sales person also never tell you that the BIG company can do anything they want to and you as the user must follow suit and you you don't like it, take us to court. We got the money.<br> <br> Vodacom answer my question: Can I lower my contract to fit my pocket as you did with your increase to fit your pocket.