To anyone who tried to access Wabi yesterday, I do apologise!
I honestly thought I'd paid for the domain name last week, only to find when I went to log in that it had in fact expired.
I immediately logged in to the domain server and sent payment through, but it seemed to take a long time for it to take effect... I even called their technical support to make sure things were ok, and was assured it would just take a little while. Wabi reappeared last night (thank goodness!) and all now seems to be back to normal.