If the charges have already been made then I'm not sure you can @Kerryb
If you want to stop NEW charges, then you need to apply a couple of bars to your account - see the guide below for which ones.
Guide: O2 BARs
To do this, you need to speak to customer services. All ways to do this are in the guide below.
Guide: How to find help & contact O2
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 Do not publish personal details (email, phone number, bank account).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
