All of this reminds me of why I gave playing in knockout comps with no dates fixed by the club many years ago. Twice in one year I was drawn against a player who could only play Saturday afternoons when Saturday afternoon was the only day/time of a week I could not play.
We had 2 policemen who could only play midweek, and entered the winter doubles. Absolutely no good for anyone that works 9-5, and is only free at weekends. Since then, the ToC were carefully written such that players needed to provide reasonable dates, which also included weekends. It was carefully enough worded so that the Committee still had ultimate power to rule on who is at fault (if anyone) when a date cannot be agreed, without any players throwing the ToC's under our nose.
We also firmed up on players meeting the deadlines, as the previous comp sec basically allowed players to play when they liked for years, resulting in carnage (matches being months behind, players putting their matches back weeks as they did not like to play in cold weather, despite them being in Winter Knockout, etc)
To be fair, since then (about 5 or 6 years ago) there have been no real issues. In the 1st year, a couple of guys in the singles were both DQed as they didn't play by the deadline, one of whom was upset by that (despite him never approaching Committee to say he was having trouble sorting before deadline). Player's quickly get used to it, and it becomes a non issue. We always made it clear to everyone, if you think there will be issues getting your match in before the deadline due to lack of availability of opponent, approach Committee as soon as you can. Hopefully we can help resolve the issue asap. If no one approaches the Committee, the deadline comes and goes, then there are no real excuses.