12GB Fair Usage Limit - Data Roaming

[DPJ]

My wife and I spent 3 days driving to Italy from the UK. I'd bought a 14 day data passport for £20 to save on the £2 per day roaming charge. My wife hadn't been able to register on the Three app. 

On the third day we both got a text saying we'd exceeded the 12GB fair usage cap. My phone said I'd used far less but I turned data roaming off as the text said I was being charged 17p per mb for excess usage 

This morning, I went through the 3 app and added up all the offending usage. It came to 

1228903 kB, which by my reckoning is less than 1.3 GB. 

So has 3's warning system wrong by a decimal place ????

[MRDB90]

Seems to be an on-going issue, lots of people reporting getting the same text after using very little internet when roaming . My partner visted Spain last month visiting family and was using the internet on the coach from the airport to destination and got a text saying had used 80% of allowance ( it’s an half hour bus journey ). Maybe it’s a problem 3 are unaware of? @DanC 

[Boingball]

I just got the same problem. Phone turned on, within 30 mins I’ve got a text saying I’ve used 80% - I looked a google maps and sent a what’s app picture. I’m assuming something is way off the calculations.