Annoyed, I began the process again only to find that my cheapie 2xtickets for £118 had now become 2xtickets for £148. Considering I would have booked the £118 tickets if their website hadn't messed up, I wasn't really prepared to rebook and pay the extra.
I called them up today and was told that the reason the website had failed was not a website glitch, despite what the message said, but just because someone must have 'got in there' before me, and booked my tickets. The error message I got was dismissed as not actually an error message, but just 'the way the system worked'.
I know that even theatre and concert booking websites, which surely have more demand on them than Eurostar tickets two months in advance, don't have this glitch; once you provisionally choose a certain concert/time etc, then you are told you have 2/3/4 minutes in which to make the booking.
This comes after another incident with Eurostar where, due to website problems, I booked my tickets with an Eurostar operator over the phone. She booked me on a train at a certain time of day and, when I got to the station to get my tickets, I found that she had booked me on an earlier train, which I had missed. I had to fight with the Eurostar staff who were demanding that I buy an entirely new single ticket. I refused, and told them to listen to my call as the operator had confirmed my train time at the end of it. Finally, they relented but only because I stood my ground.
It's annoying as the Eurostar itself is good, and it's the easiest and nicest way to get to Brussels. I just wish they would sharpen up their customer service too.