Addition to contract

Vodacom has increased our Contract without the consent of the customer. They state that this is in your contract when signed. So I have requested my original contract where I have signed for this. I have had no response from Vodacom yet. Is this not against the Consumer Protection act to add a blanket clause where Vodacom can increase our contract at anytime but us as the consumer can not cancel our contract without being penalised. Does this mean Vodacom can increase my contract by R 1 000pm without recourse? I have been a loyal customer to Vodacom for 15years. We have many contracts on our business and personal accounts - Think it might be time to change to another service provider that does not come across as greedy.