Scheduled Outside my availability?

Hello! I have worked at target for two years now in guest services. Recently we got a new ETL and he has decided to schedule everyone regardless of availability to work Christmas Eve, but I already made plans months ago. My availability says I have Tuesdays and Thursdays off always, and it’s been consistent since i was hired. My ETL did not ask me and just ignored my availability, this has happened a couple times now. Is this allowed? What should I do?