Daylight Roberry

I took a contract with Vodacom on the 25th of Jan 2013 and i was given a pro-rated airtime and also debited for half a month, and then from February 2013 i received airtime on the 1st of each month starting from february 2013 and then i would get debited on the 25th monthly. To my understanding is that the contract was supposed to have been completed by December 2014 that was when i should get the last debit. but i am still debited on January 2015 and when i called Vodacom to ask about this i was advised that there's still a debit of February that still need to go through. so now m failing to understand if this is still a 24 months contract or it has been changed without my knowledge to 26 month. and the worst part is that they say i need to call after the debit on February to cancel the contract, so how is that even possible when i got a 24 month contract. how can i call to cancel the contract after the term has elapsed? i thought Vodacom as a large brand that it is should know better, i dont need to call anyone, the term has elapsed so let it be