What happened to you sucks. You will always encounter teams that are too lazy to communicate, which will cause issues for your team, or teams that are just trying to be dicks and exploit the rules.
I'm a little surprised, however, to see this happen to a team in the high bracket. You should all have enough experience to know what to do to prevent stuff like this from happening.
Regarding your suggestions to prevent this from happening through league intervention:
- Add wildcards again: This is not possible anymore with the Swiss system. Next week's match needs the result of this week's match to seed the teams properly. This was explained in a few newsposts.
- Mercs allowed by default: It seems to work in Highlander but take a guess how long it takes until a premiership player from last season joins an open team and is allowed to merc anywhere by default. People are already complaining enough about former high tier players joining lower teams.
Just to give you some hints on how to prevent this from happening to you in the future:
- Make sure to submit your available match dates for the week in time
- Make sure you actually have enough players available that day
- Add backup players to your roster in time in case the above does not work (and the opponent does not answer to your merc requests or denies them)
- Arrange a server well ahead of the match and ask your opponent to check pings (this does not need to happen at the last possible minute)
- If your opponent is lazy to communicate, set up everything so that you do not need any communication with the other team (except for forwarding the connect string) to play the match.