I have a paid F ticket BKK-DXB, originally supposed to be a 388 but later changed to a non-suite 77W, which was fine with me as long as I was in F... This morning I discovered that my booking was changed to J and sure enough, now the a/c is 2-class 77W. The flight is a couple of weeks from now.

There are 388 and 77W (with suite) flights a few hours later and available. Do they generally allow switching flights without fees or fare difference in this kind of situation? Thanks!