I'm having the same fight with CO on CO 5 leaving LHR on 13 Jan 10. The flight was originally delayed due to weather (about an inch of snow on the ground) and then canceled due to a bleed air valve being stuck closed.

I've called customer service a few times to try to get my EU compensation and each time I call to check the status they just give me a new case number and tell me it's been submitted to a different department and that I'll get a check in the mail. So far they've been mostly unhelpful.