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

The match between Japanese versus Thailand in FIVB Olympics Qualification Tournament on May 19th was a farce for audiences. The technology used in this game seemed to be unfair for Team Thailand. Challenge was denied when Thailand got a momentum while there was clearly no problem happening to Japan Team. Substitutions were also denied. Really? This was a professional game why Thailand team could not switch their players. Last but not least, Thai coach was given two red cards which meant Team Thailand had to lose big 2 points in the fifth set as the referee gave the stupid reason that Team Thailand tried to delay the game. The truth is Team Captain and Thai coach tried to tell the referee that the technology failed and asked for some help and at least a listen. I also hated the fact that it wasn't working since the last minute of set 4 (when Team Thailand couldn't send Middle Blocker to the court, instead, they had to let the Libero specialist to block at that moment) until the “do or die” set. Again, there was no problem with Team Japan who was the host of this tournament.