1 gigabyte data depleated in 4 hours

Good day, <br> <br> I have purchased R180 airtime which I switched to data, more specifically an all network data bundle. 1 gigabyte for R 180. This was at 10:15 on Monday 13 April 2015. The same day at 13:08 I receive an sms that I have 499 mb left, another sms on the same day at 13:32 saying I have 98 mb left. And the last sms 13:34 saying that the bundle has been used up. A bundle normally last two to three weeks. How this one be used up in less than 4 hours when I have only been on my emails using a gmail account???