Prepaid airtime/data disappearing

An hour after purchasing airtime it disappears to a 0.00 balance without sending any calls or sms's - not used on data either as purchased a data bundle at the same time - data also disappeared with an hour of just sending/receiving a few whatsapp messages. And no I did not subscribe to any services or content - if I am then that is ***** because I did not agree to any subscriptions!!!!!! **************** FROM MTN