Just ring the Duty Officer during office hours and he/she will put you through to someone who can help.
Alternatively you could just try re-registering.
I do know that the software manufacturers, Thales Information Systems, had the site down in the past few days for bug fixes.
AIS is a small organisation (around 30 people) and they are happy to receive visitors, whether from a group for a tour or from an individual wanting to consult the library of foreign AIP's they maintain.
They are in the Control Tower Building at LHR so it's an interesting visit. Best contact if you want to arrange a group visit is Lesley Clayton.
Mike