Originally Posted by testman

Last September, I bought economy tickets in classes E and L. Then the flight schedule changed three or four times during the winter, and I was allowed to ask for a full refund or change my flights.
I decided to change the dates of my flights to stay abroad for a few extra days. After my changes to the tickets, they were reissued in class Y (all four legs).
I made the change about a month before my outbound flight, when most flights were almost fully booked.