Just sent them this:
Dear Sirs
To the best of my knowledge, this event was cancelled almost a month ago. Neither I, nor my fellow entrants, have received any refund of their entry fee, nor any indication of how or when this will be arranged. Many of us have emailed you about this and received no reply.
This is not acceptable and reflects very badly on Extreme Running.
You should be aware that entrants are voicing their concerns about this on webforums – see here for example http://www.runnersworld.co.uk/forum/forummessages.asp?UTN=165696&URN=6&dt=4&srchdte=0&cp=3&v=1&sp=
I urge you to address this situation immediately to avoid further negative publicity or other action by entrants.
Yours faithfully