Surely this needs to be pursued out of the jurisdiction which to tickets were purchased? That is, if they were purchased from Jetstar Asia in BKK then you need to take it up with JQ Asia in BKK. I am not saying that it shouldn't be taken up, but just that you want to do it properly otherwise you are wasting time and more money.
There is no travel insurance which you can claim on for denied boarding and then let the travel insurance company sort it out?