Cannot Link Account to O2 Login

I am having difficulty linking my account under the new O2 login regime. I have nominated a non Virgin Media backup email address, and kept the password feature. I have clicked on the link to verify my email address and clicked on the 'Link Virgin Media Account' button. I get taken to a page that asks for "Last name on account", easy to fill in. "Account Number", easy to fill in. "Area reference number", impossible to fill in. When I try to select "34" at the foot of the list, the box jumps to "31", the number above. The account is therefore not recognised. Can someone tell me if this is deliberate please?

Outlook has been unable to Authenticate two of my email passwords since last weekend, I've looked here for advice and am trying to get back into my account to see what can be done. Thank you.