Lots of things are unfair, including that blind people can’t enjoy most of the graphic elements of a movie at all for example, or that deaf people can’t hear the score, or that people with severe bladder or disgestive problems probably can’t sit through the whole thing, and so on and so forth.
If anyone ever promised you that everything in your life would be “fair” then that person did you a disservice. That would be unfair of them.~ Speaking only for myself and everyone else that I know personally, it’s a good thing that “life isn’t fair”, or we probably would have all been drowned before our sixth birthdays.
But back to your case: You didn’t like the movie.
Was there anything lacking in the service provided? That is, did the theater have bad acoustics, or was the audience disruptive (I’m assuming you didn’t watch The Rocky Horror Picture Show, where audience disruption / participation is part of the event) and not quelled by the ushers? Was the butter congealed on the popcorn? The fizzy drinks flat? The seats uncomfortable? If there was a problem with the venue or the projection, then a calm, thoughtful and dispassionate complaint to the theater manager – with a suggested compensation that would make you whole again – should be well-received by a reasonable and profit-minded theater manager.
If the problem was with the film itself: misrepresented by the trailers? unfaithful to the original written work? flatly acted or badly produced in some way? poorly edited or directed in ways that you can elucidate verbally? In that case a thoughtful and well-worded letter to the distributor can result in comped tickets to another movie that might be more to your liking.
Nobody likes to hear complaints, but business managers who know their business put more stock in one well-worded and thoughtful complaint than they put into mindless “support” by yes-men and thoughtless consumers.
You might be surprised what a “good complaint” can return to you.