PRICE INCREASE

I JUST RECEIVED AN E-MAIL FROM VODACOM STATING THAT MY SUBSCRIPTION WILL BE GOING UP FROM THE 1ST OF MAY 2015.<br> <br> I HAVE SIGNED A 24 MONTH CONTRACT ON THAT SUBSCRIPTION TILL DECEMBER 2015. HOW CAN VODACOM GO AND BREACH A SIGNED CONTRACT.<br> <br> I WILL NOT PAY THAT AMOUNT I WILL CANCEL MY DEBIT ORDER AT THE BANK AND YOU CAN DO WANT YOU WANT YOU CAN EVEN GO TO HELL I WILL NOT PAY IT.