Vodacom incompetence

I have a 20Gb data account with vodacom and my contract has apparently ended 5th of Feb no one notified me or told me it was due for upgrade so today they deduct an additional R800 odd of my bank account because now I pay month to month with the extra it adds up to roughly R1000??? When I call to find out what is going on I get told someone should've phoned me??? Yet no one did but I still have to pay surely that's not right!!!!