WiFi data disappeared

On 23/12/2015 at about 14h30 I bought extra 2 Gig data for my WiFi (R 139.00) for using until the end of the month. At about 20h00 I started roaming on the internet. An hour later I was informed that I had no data left. When I phoned Telkom, I was told that I used all of the 2 Gigs in that hour, which I cannot except, because I made no downloads or do anything else that used such a lot of data. Although I told them that it is not possible that I used so much data in one hour, they just said that I used the 2 Gigs in that hour and that they cannot do anything about it. They cannot accept that the problem is at Telkom and blaming me for the lost of data.