Escalation in 24 month contract***

I entered into a new 24 month cell phone contract with Vodacom om 7th August 2014. Today I receive this sms from them! How can this be??<br> From 1 May 2015 your uChoose Flexi 100 subscription will increase from R99.00 to R110.00 per month. Your new price plan name is uChoose Flexi 110. For more information visit [URL Removed] T&Cs apply.