High data consumption. They blame it on my phone.

At first I thought I was using too much data until I saw similar complaints from vodacom customers. I lost too much data and they blame it on my phone. I normally turn off mobile data for apps I don't use and when I go to sleep I turn off my mobile data. I could not have consumed 3 gigs in less than 24 hours! What's worse is that I couldn't even load data on my phone after that. Got an error message saying I'm not authorized to use the service. Went to their Clearwater branch but wasn't assisted. Had to get an MTN sim so I could at least function but if something happens to my phone with an MTN sim they'll refuse to let me claim from insurance. This is not acceptable! We pay too much for data. I want a refund.