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

While not a sport player myself, I am an avid fan of the Thai women's volleyball team. I feel the team was unfairly treated, with the system not responding to the Thai coach's request for player change or challenge at the critical juncture. Put simply, if the old traditional method had been in use, there would have been no problem and Thailand would likely have won in set 4 where they were unable to make a key player change and was instead penalized for pointing this out to the referee and asking for clarification. The charge against Thailand in Set 5 was for delaying tactics; the Thai team was leading well in the final short set, not a situation for resorting to delaying the game. However, when the system failed to respond to our requests for player change and challenges, the team had every reason to point it out to the referee and ask for fairness.