Easyjet (with whom I personally have so far had very good service) are certainly not the only airline to induce annoyance by attempting to evade the full obligations imposed by EU regulation.
My wife and I had a protracted run-in with BA a couple of years ago after they cancelled the first leg of a round trip, put her on a much later flight, but failed to tell their computer which then declared her a "no show" and cancelled her return flight from Gibraltar. (and guess what, she was able to get a seat home on EZY)
It took about 6 months of letter writing and the beginning of legal action before BA coughed up the compensation.
If I were you I'd assume that EZY take a similar path of trying to get away with offering as little as possible in the hope you'll take it. The amount of money owed by the airlines for full compensation payments is probaly staggering.
Just keep trying - you'll win in the end, even if it does take initiation of a Small Claims Court proceeding. That seemed to be the final tripping point for BA.