Need some advice

I'm currently a junior in college, and I came home for my winter break with the intention of returning to work during this time. I had a conversation with my SM on December 18th, and we agreed that I would return to work on December 19th.

So, on the 19th, I showed up at 8:30 AM ready to start my shift. I spoke to my ASDS to get back into the system and be taken off leave. During our conversation, I informed him that my last working day would be January 14th. However, about 30 minutes later, I was called into the ASDS office again. He instructed me to meet with the SM in the training room.

In the training room, my SM informed me that there was no space for me at the pro desk, and instead, I would be placed at the service desk. She then asked me to go see the ASDS for my schedule. When I met with ASDS, he asked if SM had told me about the shift, to which I replied no. ASDS then took me back to SM to discuss the shift. SM informed me that I would have to work the closing shift.

There were three other college students who returned and they were able to receive all of their hours back and didn’t have to transfer departments but for me it was a no. I have been able to come back to work every winter and summer break for the past two years but suddenly I can’t. Since I can’t close on weekdays, they are only allowing me to work 6 hours on Saturdays.

I explained to SM that I couldn't work the closing shift because, on weekday afternoons, I have to visit the Orthopedics due to a car accident I was in last month. I inquired about any available morning shifts, but I was told that there were none, and my only option was to close the service desk.

Should I just quit?

edit: The other 3 college student who returned we able to go back to their regular hours and position. For example, one other guy at the pro desk returned and received his regular hours. Does it seem like they maybe are trying to force me to resign?