I have just been sent an answer:
We're sorry to hear the site is giving you some trouble.
Unfortunately some of our users are currently having trouble accessing their accounts. It appears your account has been affected.
Our Help Desk and web team have been notified of the issue and we are currently investigating. Our team will work to implement a fix as quickly as possible.
Thanks for reporting this issue and for your patience.
We'll send you an update when account access has been restored.
So they are trying to fix it. I hope they will succeed ASAP.