I don't see that you have any basis for complaint. It's
your responsibility to protect your own hearing. That means having proper and adequate equipment to do the job.
Plus, you knew you'd be at an indoor range where other shooters may be shooting large caliber handguns, but you went anyway, right?
If I'm at the same range as you and I've paid the same range fees and am shooting a .44 Magnum, you're going to complain because you think it's too loud for the indoor range?
Maybe try to tell me I can't shoot my gun of choice there? That won't work at the indoor ranges around here, especially the two I use.
There's an old saying: If you can't stand the heat, stay out of the kitchen.