Given that you refuse to provide any specifics, I can only offer a generalised response.
Your Union is YOU. Look up the definition.
How many of your colleagues are volunteering their time on their days’ off to try to resolve your problems?
Having a whinge on PPRuNe because you have to lift a finger to help the Union? The problem is you.
If you don’t like the way your Union operates, get involved... you might be surprised by what you learn.