OP here. It all came out right in the end! The server was bought to it's knees. Sysadmin thought I (as a very new customer) was up to something bad (my email address is james@rootdev.com and he feared I was a bad actor) and froze my account. The webserver didn't know what to serve and decided the best bet was to serve the first thing (alphabetically) that it could find (some insurance company beginning with the letter A). Now on a different server. And got to meet my lovely sysadmin who put everything right straight away (who wasn't even pissed off at me). What a day.

Thanks for the postmortem. Sorry things got a bit more hectic than you'd hoped but it's interesting to know why.

Yeah, things did get hectic. Still pretty busy today. The support and feedback from here was amazing though. I didn't expect that. It really helped me get through. And takeaway food. I literally posted to HN just as I was about to go shopping cos I didn't have any food - I didn't make it, still haven't!