I first got a reply that should have gone to another trader

Nice protection of privacy - not! Then when they finally commented on my trade they of course declined it on the same grounds as you've all mentioned above. I've replied back that I'm not accepting that since the fault was solely at their end and that a better back up system should have been in place.
Considering their phone lines where blocked I say we have a very good case against them and suggest a joint action against them. My loss is too small in monetary terms to merit that I contact a solicitor on my own, but if there's a group of us with the same claim it shouldn't be hard to find a lawyer that will take it on.
Secondly we should definitely write a group statement to the regulators because the way they've handled this is totally out of line.
Let me know your thoughts.