MYSTERIOUS DATA CHARGES

Lately i was perplexed by my vodacom data usage and i see i am not alone given the numerous complaints about unexplainable data charges, missing data ect. Vodacom when called gives you the runaround with no clear answers. <br> Due to unexplainable data charges over the last few months i got the vodacom app on my cell to track costs/data and this is were it gets very interesting.<br> <br> As at 15:30 today my vodacom app showed that my bill was around R 2300 and i had no available data as it was used up some time ago. Around this time i received a sms from Vodacom with an offer of 1GIG for R59.00 valid for 7 days. I purchased this and it showed on my app as being available, i thethered my cell to my laotop and used it for about 15 mins..i watched some videos. Immediately after disconnecting i refreshed the app to see what data was used and it still showed same amount of data as before i used it as tether...i refreshed it again 20 mins later and NOW it showed that no data was available and my bill at 19:00 was now showing R 5300.00. So besides not geting my 1gig i bought..it ment i used 3.8 gigs from 15:30 or so to around 19:00..3.8 gigs in around 4 hrs...?????