ai is pretty bad with offering refunds in situations like this....i once got downgraded on a flight where i had bought my business class ticket months before....the refund they were offering me was the difference between the low business class fare i bought months ago & the high economy fare available at the last minute....there was hardly a 15% difference between the 2 at that time whereas when i bought the ticket the business class fare was 4 times the lowest economy fare....