Hi srmtvr
Welcome to the community forums
Sorry to hear that you've not been able to register for your online account.
The area code should be with/next to the information that advises you of your account number, This is usually shows as an area reference/ area ref:/ area code on our communications.
If you've not been able to locate this, please join me on private message and we'll be able to locate this for you at our side if you need. You can see your private messages at the top of the page, in the envelope icon or if you're using a smaller device, you can see your private messages by clicking on the Virgin Media logo at the top right and select 'Messages' from the drop down.