Zaxby's review: no hours for three weeks and then was taken off of schedule without notification

My name is Theo. I was hired in July and worked about 28 hours a week. I worked 28 hours a week in the summer, but my hours reduced when I went back to school. I worked about 10-14 hours a week but one day when I called in I was told that I did not have any hours. I was told that I was not assigned a time. Today, after 3 weeks of not having any hours, I was told I was no longer on their schedule. I do not understand why I was never contacted or given an explanation. I think that it is pretty sad that I was never told what I may have done wrong. It is pretty frustrating to not know. Isn't it unethical to be letting go without a notice or even a meeting. I say those are poor work ethics.