Data usage accuracy

[EEG]

I recently switched from Virgin mobile to 02 mobile, primarily because the signal is supposed to be better in my area.

I was on a 10gb tarif before but never got through more than 3gb a month, so when I moved to 02 I switched down to an 8gb tarif thinking that would be more than enough plus some leeway.

Now bearing in mind that when I'm at home I use wifi all day, so not using mobile data, and suddenly I'm apparently now getting through nearly 5gb of data a month according to 02. Coincidentally I'm now getting messages regarding upgrading my tarif...

Just how accurate is the recording of data usage and has anyone else found they are suddenly using more data than they ever have even though nothing about their usage has changed?

[MI5]

@EEG 

There's no widespread issue with O2 data recording and it's not a common complaint (although does crop up occasionally).

The best thing to do is reset the data counter on your phone to coincide with your O2 billing cycle and check what your phone records compared to your MyO2.

[gmarkj]

If you are using an Android, you can download apps to track your usage.
Check that WiFi Assist (or similar) is off, and whether or not you have a setting for swapping to mobile data if the WiFi signal drops.
There is a setting for WiFi when the phone sleeps - make sure this is off (you want WiFi to stay on at all times).
You should also be able to see what is using the data in phone settings.

[Bambino]

@EEG If you're indoors all day on WiFi, manually switch off your mobile data in Settings, and get into the habit of switching it back on when you go out.