Yanking the thread back on track, I'd say that it happens. Don't blame yourself: they had three characters with high will saves. Their cohort will now always devote a spell slot to spells that get rid of enchantments. If you never use things like enchantments and compulsions, it somewhat undercuts the classes that have good will saves anyway. (As a player, if I'm sure that the DM won't use charms and compulsions, I'll not cover that weakness, which makes my character slightly stronger than it should be.)
Use it to your advantage: they're high level characters who are going to be missed by their patrons. Let the patrons bring them back so as to have the players owe him a severe debt of gratitude. Or have the villains use neutral clerics to lure them back from death and let evil ensue.
Finally, you've neglected to tell us the most important bit: did the players have fun? Yes, high stakes playing can be fun and yes, anxiously waiting out confusion effects can be fun.
And getting to smack other characters without consequence? DEFINITELY fun.