If you have and the old sim no longer works you would need to switch the (new) phone on and off so it registers the change.
If you haven't, then call CS (numbers here -
http://www.o2.co.uk/contactus) to check everything is ok.
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 Do not publish personal details (email, phone number, bank account).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
