So a while back,at the beginning of September, I asked my shift supervisor if I could have 2 days off a week because I was starting an internship and had no other choice than to take those days off work. I'm a full time college student and really had no other choice, I'm an unloader and our quad always has people being sent home EVERYDAY, so I figured it wouldn't be that big of a deal anyway. A few days later he told me it was ok, but I have to be the best worker in the quad. I always work my ass off when I'm there, I may not be the best, but I always do my job the way its supposed to be done. So last week I was headed to work and my car started smoking, broke down, I was about an hour away so their is absolutely no way I could've made it to work. I called in and let them know I couldn't make it, my car broke down, blah blah blah, mind you I did not just not show up, I let them know I wouldn't be able to come in. A few days ago the same shift supervisor comes up to me and starts telling me my two days off are gone now since I called off. I tell him theres no way I can do it because I already made another commitment to my internship based on the fact he gave me the go-ahead to take those days off, and he then proceeds to threaten to fire me and tells me I should start looking for a new job. I guess my main question is, is he allowed to just take those days away he already gave me?