Tracking call and data usage history on an O2 pay as you go

[Steve2811]

Had a pay as you go sim for years but recently bought a new Nokia phone and transferred the sim successfully in to it.

However I'm noticing that my balance is going down slowly  every hour or so  by a few pence each time without actually using the phone for calls or texts and wonder why. Is it because the new smart phone is using data behind the scenes. I have the wi fi turned off and never use the phone for internet searches.  Maybe the built in apps are doing something in the background all the time although I never download any apps myself.

My previous semi smart Nokia phone only showed a reduction in my balance after I used it for calls and texts.

Any ideas anyone?  

[MI5 · Accepted solution]

@Steve2811 

Turn off mobile data in the phone settings as it will be that using your data.

[Steve2811]

Thank You M15, the mobile data was on as you suggested so I turned it off and will monitor my credit.

Appreciate the very quick response. I am very much a novice in all things smart phones. 

[Steve2811]

Thank you very much M15 for the very quick reply. Mobile data was on so I turned it off and will monitor my credit.

[MI5]

You're welcome