Quick depletion of Data Bundles

For the past 2 months I have had a problem with my data bundles getting finished before time. I normally buy 2G & use my internet more or less the same all the time. This month I decided to buy 5G for R 399.00 because I noticed for the past 2 months they got depleted way beforetime. To my surprise I just got a message that am left with 4.92MB. I then called Vodacom to check what the problem is and I was told by PALESA with a BAD attitude that 1. have automatic updates (which I don't have on my device because I deactivated them). 2.The speed of the internet I use is the problem. She didn't want to listen to me instead she was talking while I was explaining to her which irritated me to the core. I eventually asked her if she is going to listen to me or if she is going to continue talking when I'm talking because obviously she wasn't listening to me. Stinking attitude again when she said I must tell her when I finish indicating that she was fed up with me. I would not be calling Vodacom if I didn't see a problem. I have had my phone for over a year now and I have never experienced such a problem with my data bundles. I have been buying 2G or 3G & it would last or expire instead.