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

After watching the Women Volleyball Olympic Qualification 2016 match between Thailand VS Japan, many questions had come up in my mind, many questions that I, and others, seem like cannot find the CLEAR answers.

I'm Thai but I did cheer both Thai team and Japan team, I do have many favorite players in Japan team as well. What I expected to see in this match was enjoyable and excited game, as it was, until the end of set 4 that Thai team cannot change the player due to an error of something we called 'Technology' and ended up with 2-2 set all, have to play 1 more set (set 5) to find the winner.  I am not saying that denial of substitution in this set leaded to the defeat of Thailand, just have a little curious about technical errors happened.

In the final set (set 5), everything was going well, until during the score 8-12, which Thailand took a lead at 12, Thai team did called for challenge to see one of Japanese player did touch the opponent's court beyond the centre line or not but the referee denied with no reason. For this case, I am not sure about the rules in detail but I did know that each team has RIGHT to challenge 2 times (which I'm not sure per set or what). I don't think it would be make sense if the referee said Japan did nothing wrong so Thailand did not allow to challenge, how come you were so confident about that?

All of that I wrote until here was just an appetizer, the main dishes was come after that. When Thai team got back to the game after called for time out, the referee called Thai captain and gave the red card to Thai coach, also, 1 point gave to Japan, cause the score now 9-12. Then, the game continued and the situation changed, Japan took a lead at 13-12. Thailand called for the substitution and once again an error of technology was brought to be the reason to not allow Thailand to change the player, moreover, 1 point gave to Japan again! For trying to explain that there was something wrong while Thai staffs want to substitute the player, Thailand had to pay MATCH POINT to Japan. What an unbelievable judgement, I've never seen something like this all the time I've watched volleyball, NEVER! 

It's kind of heartbreaking after seeing Thai players in tears after the UNFAIR match. I'm not saying that Thailand should be the winner in this match, although my heart shout that we should win! What I want to say is we'd rather lose in FAIR game, which means after we did our best, we tried very hard but in the end we cannot defeat Japan, this is acceptable. We'd rather lose by our errors than some CHEATING tactics.

Sorry to write so long, I just hope we can get some explanations to clear our suspicions toward this match.