Thanks Jeff for the reply.
I would have thought if there was scheduled maintenance it would be a good idea to temporarily take down the sign up page or at least provide some sort of warning or notification on the page to deter people from trying to sign up during this time.
The page says 'do not click back or reload the page to avoid duplicating your purchase'. I'll try again as you have suggested. Could you please check that my purchase wasn't duplicated?
Thanks