MTN - Depleting Data and Airtime within minutes

I recharged my wife's cell phone with R60.00 on Sunday evening in order for her to convert the airtime to data. She then converted the airtime to data and switched off her data and went to bed, upon her waking up all the data and remaining airtime had disappeared. When she phoned the MTN call centre she was treated like she knew nothing about how a smart phone works. She was told that she left Amazon open and it depleted her data. My wife has never bought anything on Amazon let alone download the app. I then loaded the same amount on another MTN sim card we have yesterday, within 5 min 300mb of data and remaining airtime was depleted. And how is this possible to have two different cell phone makes (IPhone and Sony) and the same apparent amazon depleting data which was not even open nor any apps downloading. We are now in a situation whereby we have to port to another network as her work requires her to be online in order to utilise google maps because we are not even sure it's worth staying on MTN due to such poor service.