OK, finally got through to BT on the 'phone. There's an issue with their main email server (or servers?) and they are working to fix it ASAP. Worst case might that not be until tomorrow morning, but hopefully much sooner. They advise waiting for a couple of hours before trying to log in again. Apparently too many failed email logins can cause you to be locked out altogether, just to add to the stress! They appreciate the difficulties we all have as a result of this issue and the person I spoke to was very apologetic - obviously it's not the call centre staff's fault so I was calm and polite, although I'm very unhappy and made that clear.
