Missing Data!!!

I have entered into a contract with Vodacom for a 5GB DATA top up plan!<br> <br> The first month, the data was loaded late - due to technical problems....the second month my data ran out by the 20th of the month - when I phoned them it became clear that by some means my 5GB data was now changed to 3GB...??? That was rectified, then the 3rd month being October 2015 - my 5GB data was loaded according to VODACOM on the Thursday Night at 00:00! By the Friday when I got back from work at 12:00 midday, I could not log into the account - my data bundle was depleted?? Really not even 36 hours! Of that 36 hours we were asleep for 12 and at work for 10 hours that left us with 14 hours in which WiFi could have been used. Imagine the mp/s!! Never ever was internet in our area that quick! Needless to say, yet another call was logged - a technician phoned me back - they said that I have used everything, but means of my on and off facebook visits and whatsapps that came through! But they are willing to give me another 5GB for the month! this time I received an sms on my Wifi sms's. That was loaded on the Tuesday afternoon and by the Friday it was all used up again! Impossible!