Hi Irena, and a warm welcome to FlyerTalk.
I too am flying BA, due out of BKK on 30th (I'l in Jakarta at present on a side trip from Thailand).
Advice above is sound, and there is a BA thread which is very active, and where an experience BA FTer can probably assist.
An option might be for you to consider flying out/back from Thailand immediately to another nearby destination. This will affect any accommodation you might have booked, but means that you can still travel.
Cheers, TK