Contracts work two ways....for the company and against the pilots.
With the market situation for pilots....getting too rowdy draws the kind of attention you do not care for long term.
Boss Fellahs are used to running the show and don't care for interlopers who get into their turf.
If they are paying you for the overtime and making other compensatory measures....your screaming about it being unfair shall fall on deaf ears I would think.
Does the Contract state you can refuse overtime or extra shifts?
Read the Contract very carefully before you walk out on that long skinny plank.