The Data Sense app on my phone reckons I have used 2.5GB of mobile data in the last month compared to nearly 5GB of wi-fi data.
But the My O2 app on my phone reckons I have used just 18MB of mobile data which seems an unlikely small amount. But it does also say "Left until 6 Aug 2015 - Unlimited" so does the 18MB mean only what I have used in the past couple of days which is possible as I have not done any mobile streaming or downloading or even web browsing in that time as I have been mostly at home or connected to public wi-fi hotspots.
But the My O2 app on my phone reckons I have used just 18MB of mobile data which seems an unlikely small amount. But it does also say "Left until 6 Aug 2015 - Unlimited" so does the 18MB mean only what I have used in the past couple of days which is possible as I have not done any mobile streaming or downloading or even web browsing in that time as I have been mostly at home or connected to public wi-fi hotspots.