I work casual, and I also volunteer once a week on Tuesday nights. I have volunteered longer than I have worked in my current occupation, and everyone I work with knows that I volunteer.
I told my coworker, at the workplace where I work causal, who does the rosters that I am able to work Tuesday nights provided she discusses it with me first in case I am in charge of what is happening at my volunteering that night. I tell her this over and over again, and she's good for about a month and then goes back to just rostering me on and I once more have to remind her of my previous commitments. I'm sick of having to tell her.
Other casuals have asked for specific nights off, and we're pretty lucky that none of us clash with nights off that we want, but they very rarely are asked to work the nights that they want off so I know it's not just that she is forgetful. Maybe I'm being paranoid or judgmental, but I constantly feel like I'm treated like crap because I'm the youngest on the team by a lot, and also my parents left with bad blood from the same company and they're taking out their frustration for that on me.
So what can I say to her that might make it actually stick that I need to be asked prior to working Tuesday nights?