Hlala kwabafileyo

I am having account with multichoice/Dstv which is locked for 24 months and the premium is R664. My balance now ballooned to R710 and you can see they trying to squeeze their explanation ,all these month of the contract i was paying R664 as per contract. What changed are they breaking the contract? What is new that i added for the premium to increase. Why am charged prorata,what did i change