Unionize.
It is not your responsibility to sacrifice for your job to stay afloat.
Discuss your salary with your coworkers.
Call out the bullshit of managers, HR, and owners.
Your free time is your time.
Look for legal representation if you feel that you are illegally exploited/abused.
If a coworker is being exploited/abused, say something.
Your boss isn't your friend, you are merely the help.
Don't let your employers dictate your salary. Your time is what you alone dictate what it's worth.
You don't have to excuse, nor explain, your unavailability on your day off.
If something you feel important comes up, your job should fall to the back burner.
Please add if you feel i missed something.