Contract Price Increase

I cannot understand how Vodacom can increase their contract prices whilst the contract is still in progress. I can understand if a new contract is signed, but for existing contracts...??!?!!? <br> <br> Is this in line with the Consumer Protection Act? When i signed the contract, i don't recall the person ever telling me about contract price increases whilst the contract is in progress. Surely this must be communicated upfront? Is there some bigger crisis at Vodacom that they suddenly need additional fee revenue?