Airtime

I have noticed over the past couple of months that I have been buying more airtime than usual. I receive R200 airtime and 500mb on a monthly basis. Most of the time I top up my Data with 1gig as this usually lasts me quite sometime. <br> <br> On the 13th of this month I had been sent my usual amounts as per my contract. By the 17th I noticed that all airtime had been depleted. How is this possible?? I must have only made two (local) phone calls and +/- 2-4 minutes each. Surely that is not sufficient enough to deplete a full R200 worth of airtime. <br> <br> I have checked my APN settings and nothing has changed. <br> <br> Further to that I had purchased a further R30 airtime from which had gone within a day and today I have purchased R60 airtime so I can stay in contact with people! <br> <br> I still have +/- 733mb of data on my mtn phone yet I still see that the airtime is being used. <br> <br> This is ridiculous and I probably will never see that money / airtime again. EVER! I will not be refunded as I do not have records of how the airtime or data has been used. So what are the chances?? <br> <br> I am very positive that this is not the first month. <br> <br> A new network is my next move.