Breach of Contract : Pricing Increase MID Contract

Received a mail from Vodacom stating that from 1 May my 24 month subscription will increase.<br> I signed a 24 month contract at a specific price not a month to month contract.<br> If they want to increase they should give me the opportunity to cancel<br> This is a breach of their 24 Month contact.<br> I spoke to a lady at the call center who was just as useless in answering why the increase etc.<br> <br> This is unacceptable.