2GB Date Bundle runs out in one hour

I have recently purchased a Wi-Fi device from Vodacom on a 2GB package. On the 1 August my bundle was activated and within a matter of a few hours the data bundle has run out - no updates or any background downloads was done, this was purely used for mail usage. I recharged my account on 3 August with another 2GB and again exactly the same happened, data ran out within an hour or two. Just to make sure that the problem was not on my side I was stupid enough to buy another 2GB bundle, needless to say that the bundle again ran out within less than an hour. I am 100% sure that there were no downloads or updates that ran during this time. This is a R450 wastage on data which I never received any value from. This is not acceptable, and this does not happen on the MTN data package that I use as an alternative.