Are you the guy who sat behind me and fell asleep during helper orientation?
I know you said you're a loader, but from what I read, many loaders work as helper as well.
You didn't explain how or WHY you missed. If you have medical conditions, that's one thing. If you're hungover after every thirsty Thursday and have one unexcused, uncalled absence a week, I'm surprised you haven't been fired yet. I'm pretty sure latter isn't something union can help you with.