changing the rules to suit yourselves

Today I get a sms from Vodacom. Saying from next month my contract has gone up. I only upgraded last year and as far as I remember I signed a two year contract with you. I suppose YOUR terms and conditions say that You can change your prices as you feel it suits you. I never have good signal. My calls get dropped frequently. Your data charges are left to be desired and now you ripping me off more. Clearly this is not a service provider I would like to continue having a business relationship with. I wonder how many more angry customers you have now???