App not updating data usage

[BK123]

Currently in France so need to keep a check on usage but this month app isn’t updating what I’ve got left.  

[Enlli]

Two things 

The App seems to be giving problems at the moment so best using My O2 from the Web

Roaming usage may be slower in appearing as it is passed back by the roaming networks.

[pgn · Accepted solution]

And a third thing: your phone keeps track of data usage itself, if a reasonably current model, @BK123 

 For android, se section half way down this page: https://www.lifewire.com/track-data-usage-on-your-android-121660

And ditto for iPhone here: https://support.apple.com/en-gb/HT201299

[BK123]

Thank you.  I’m not sure it does though as my phone won’t know when my next bill is due?  Correct me if I’m wrong or can you point me to the place where I’d find the answer.  

[pgn]

Mine, on android, is set to zero automatically on my billing date, 1st of every month:

And I have set a warning too, so my phone complains at me as I approach that threshold, @BK123.

It is usually pretty close to what the MyO2 App reports in the UK: