My post was to explain how to use the BA search engine to produce all availibility. The OP said there was none. There is in fact quite a lot - so long as "you're prepared to be flexible" as I said in my post.
What I said was that there was no useful availability. I need to travel with my wife and I have over a million miles most of which is due to flying. I am unable to obtain 2 seats together on 1 flight as per BA requirement for using a 2 4 1 voucher. Indeed I have yet to find a day when i can get two seats on different flights. Stopping in SIN, BKK or both is an option, but even that did not help. In any event I do not wnat to be there for week in either direction and this the extent of the availabiltiy if traveling alone. using QF is an option but at a far higher redemption rate. In my experience they too restrict availability to 1 seat at a time also and BA vouchers do not apply.