Night shifts

When I was hired, I wasn’t made aware I would be working from 12am-8:30am. I was told there was only one early shift, and that was 4am. They said I would RARLEY be working 4am shifts. She specified rare. But I’m working those exact shifts Friday and Saturday, as well as working from 12am-8:30am Wednesday and Thursday. These aren’t the hours we agreed upon. I was also hired for part time, and they have me on full time hours. Just because I said I was available 6 days out of the week, doesn’t mean you can make me full time! I’m a college student. Wednesday’s are the WORST days for me to be working from 12-8!