First :
Get a lawyer
Second :
Record everything you do remember
Third :
Next time when you withdraw money make sure you video the whole procedure. So you have your own evidence to back you up. Do it over and over again to see whether it'll happen again.
Not just Sri Lankan Air but you have checked other leading airlines in the world we will find most of them are doing tough. For an example check Qantas.
The government has no control over who's going to fly or buy tickets from the airline. ( except for some circumstances )