Please give a legit explanation why team Thailand lost two points and does not allow substitutions s

I've watch this volleyball game, I saw over 100% effort and intention of all Thai players. But when it ran to the 5th set, I saw all spirit of Thai players was ruined by unreasonable judgement of the referee and there's come the winning of Japan team.
I'm not a big fan of volleyball game, but this is the second time that Japan did it to us, I won't mentioned about the first time but what happened in this time made me feel so disappointed.
So I was questioned by those dirty tactics why there's no sportsmanship in a sport game and what is the meaning of being the winner by a dirty tactic out of the court.
Does volleyball should be continuously call a sport when there was a very well prepared cheating next to the volleyball court lines?
Or can we still believe in the judgment of the referee?
The highest dream of athletes is Oympic games so they trained so hard, being under a huge pressure from their nation's hope and played with a heart whether there's win or lose.
They're trying so so so hard to get a position in a world competition level but all of their trying have no meaning when the cheating, unfair judgement or anything you called that action happened to them.
I was questioned, Did all lifetime practice of Thai volleyball players would be ruined in just a couple minutes by the unfair judgement?
I would appreciated if there's will be strictly investigation of this game because sports was built to teach people the teamwork process and teach people to accept whether win or lose by their spirit not by cheating.