Data charges incorrect again

After massive data charges in the past I have ensured to add 2Gig's to my current contract on my phone. I have a total of 3 Gig's during the day and 1 Gig at night. The Samsung phone keeps track of my data usage and I ensure that I do not exceed this. My usage for March was 2.6 Gig as per my phone. Big was my surprise when I received an account for R1800 compared to the average R800pm. <br> When I called the help desk they believe it was due to data charges. They believe that once again I was charged out of bundle charges. I have to wait 14 days to get feedback from accounts and in the mean time I am R1000 out of pocket.<br>