None of this would be necassary if you just set the damn dates.
If people aren't there on the date they are supposed to fight, disqualify them. It's quite simple. Just set dates 2-3 days in advance, then when you can, talk with the competitors, and tell them the time. If they just CAN'T be on at that time, try to reschedule it. But they would need to tell you they can't make it before the match, not after it.
This way you have DEFINITE matches, that are going to have someone as winner, or two losers. Not matches NO ONE can watch, because you hold them whenever the two competitors are on.