Unrealistic data usage

We were automatically upgraded to the smart voice 300 package, we were told that based on my Moms usage, this package will be the best Prior to this upgrade, we would buy data to the value of 1GB and this would be sufficient for the entire month Since the upgrade which is inclusive of 5GB, My mom’s data finishes within two weeks I have been on the phone almost the entire morning between technical and billing and each department refers me to the other I want to know, how is it possible that 5GB worth of data gets used up by a pensioner that does not FB, Google, YouTube etc Which other numbers are connecting to the wifi , so that we can understand what's going. No one seems to be able to assist me... I want to know what / who is using up all this data My Mom is a pensioner and cannot afford to be paying for a package and buying data additionally If this does not get resolved, I'd rather cancel this Telkom package all together and get her a Cell Phone through an alternate service provider