Is there any way I can be denied a vacation? I don't mean for a specific date, but for the entire year. I'm having trouble getting someone to take over my 40 hours (file maintenance) and my boss is saying things like "if its a heavy week you ain't getting a vacation" but if my "relief" is only available on heavy weeks, then how am i supposed to get my week off? I have been waiting about 3 months and still no dice.
This may sound like a broken record, but you need to contact the union. They can't deny you your vacation. It's not your problem they can't find someone to take your place. They can bring somebody in from another store.
Talk to your union asap* if it's in contract that you are entitled to a vacation, then they can handle file maintenance without you. Call in from another store like the poster above said.
*be prepared for subtle retaliation if your manager is a d*ck.