I could also have turned on Spend Control, which I've used successfully in the past. I didn't do that because I was so sure I'd turned off data. I'm the geek in the house and that was my job. I thought I'd done it but I screwed up. Mea culpa and all that.
Her bill arrived today. 67MB which cost $670. Ten times the usual monthly cost.
My lady is quite upset but adamant that no data-using applications were knowingly used, just photo's taken and texts (non-MMS) sent and received.
The LG G2 Mini reports on data use by application. Here's a screen capture covering the dates in question.

All this going on in the background!
Lesson 1: Turn off mobile data. I'm off to the tattoo shop to get this written in reverse letters on my forehead.
Lesson 2: Just in case, turn on Spend Control anyway. This will help if data is accidentally turned on again.
Lesson 3: If you do make this error, do it with Vodafone or Spark, not 2degrees. It will cost you half as much. Three 25MB data packs with Vodafone cost $300. Spark for Pay Monthly customers charges $5/MB so $335 for 67MB.
We are both happy 2degrees customers, particularly about calling and data value for money. Except when in Raro ...