Depends on what type of deal he is on @Linda11
o2 don't offer the traditional PAYG service anymore (where you put credit on the phone and use that each time you call/send a text/browse the internet).
The deal now is that you buy a bundle each month, and depending on which bundle you get there is an allowance of minutes/texts/data that changes.
If you are on the old style, then you need to make a chargeable action and/or topping up every 6 months.
As for how to top up, all ways are in the guide below.
Guide How to Top Up (PAYG)
Please note, this is not customer services and we cannot access your account. Do not publish personal details (email, phone number, bank account).
Link to our guide on how to contact them can be found here
