You obviously haven't flown the MEL-BKK route that often recently (i.e in the last 12 months). 90%+ of the time the aircraft has been the 200ER with angle flats pretty much the same as the 747. You would have had to get extremely lucky to get the 300ER with flat beds, so using the word 'always' is a bit OTT. So at the end of the day you got what you paid for. You had no 'right' to be put in the F seats.

I feel for you with the luggage delays as that is always crap and is definitely something worth filing a complaint about.

The seats you got isn't worth complaining about, as you got what you paid for.