Cheers for all the replies chaps, some food for thought. I just wondered if it was worth me doing it through the EasyJet site directly, or through a third party like Batch suggested.
What did piss me off a little bit about EasyJet (completely unrelated to compensation) when we checked into the flight this morning at 4.30am was that despite us paying for second row seats (I am still walking with a crutch) which we had on the first flight, we were given row 21. Of course we only checked the boarding card when we were nearly at passport control before realising. It took about 10 minutes of 'discussion' before they gave us the seats that we had paid for. I don't really know how difficult it could have been to made the amendment. They did the same with a women in a wheelchair who could barely walk as well, pretty shocking.