Data dissapearing Vodacom no help

Yesterday morning i had 2.2Gig data on my phone, when i got to work i started getting SMS's saying my data is almost up. i checked my Background App Refresh and it all swithched off. I bought 250MB, so i switched off all my app's. i loaded another 1G (R149) and on my way back from the shop where i bought it i started receiving sms's again saying my data is almost up. Now its 10min from the shop to my work. i phoned Vodacom twice, all they did was load another 2Gig 10min later all the data dissapeared again. so i phoned again the lady said that i was on the internet for an Hour. which i explained to her that all my app's are switched off i cannot go on the internet. so i went an bought another 1Gig data. (149) which was gone this morning when i woke up. Now i would like to know where the problem is. i cannot go on the internet in my sleep. They should replace all my Data which "Dissapeared in thin air"