Contract price increase

So today I got a mail from Vodacom saying that they are increasing the monthly cost of my Smart M contract from R299 to R319. Now although the amount of R20 isn't much, if you put that into perspective of someone that took a new contract a month ago he will be paying more than R400 extra over the lifespan of the contract for no additional benefits. I find this ********* and unjust! I know that they will probably have had some ridiculous footnote somewhere in there T&Cs that will allow them to do this. But what urks me is that the way I see a phone contract is: \Hey I am willing to pay that much per month for those benefits for the next two years"not \""Hey let me agree to pay you for 24 months what ever you decide to charge me for the same benefits\"". This isn't car insurance where you can cancel your policy when you are unhappy with the increase that was app**** to your policy. Disgusting behavior Vodacom! You have lost a loyal customer."""