Change fixed contract fees within 1 MONTH!

With reference to my previous two reports, within one month, of my extreme dissatisfaction with Vodacom today I receive an email saying that my Smart M subscriptions are both going up with R20. As far as I am aware, I signed a fixed contract for a 2 year period - what is the point of such a contract then and Vodacom running a deal like that and then just come and change the price WITHIN ONE MONTH! This is NOT what I signed up for this is ridiculous, I am in a fixed contract. Once again, you advertise something and then end up doing something else. What is going on at Vodacom??