Emergency...

My camera's broken!  This is a quick Alfred shot taken with 'the little one'.  My 550D won't write to the card.  I've checked and changed cards, nothing's wrong with them, the camera just won't record photos when I take one, it just freezes trying and doesn't even show a quick preview or error message.  I can't even switch it off to try and reset it - I have to take the battery out.  I am gutted.  I've used it every day for nearly three years...  :-(