My experience of the mail server switch-over hasnt been smooth, so they may well have a lot of customers to deal with.
Is it an issue with email?
Thunderbird resets all your local folders when you change to the new details. I hope you have a back-up of them, because it seems it deleted all of mine!!!
Luckily, I had only recently changed HDDs, and still had a copy on the old HDD, as my normal monthly back-up failed (at some point Mozbackup decided it was 2008 and I was with my old ISP; the most recent backups have all the mail, but none of the Aquiss settings)