I apologize if this doesn't fit here so if it doesn't, please point me in the right direction.
My friend (let's call her Kate) had to call out today because of an issue with her school. Kate has only had to call out once because her car had a flat tire and has been working at her job for three months now. She has been falling behind in her classes because even though she is working part-time, she still ends up working about 5 days a week after her classes and barely has enough time to get her schoolwork done. Today, she sent a message saying she could not come in because she needs to catch up on her schoolwork and that she will be there for her shift tomorrow. She gets a text saying “No, you have to come in because someone else called out.” Is there anything she can do? She doesn't want to get fired (I don't think she will) and even if he did, then he would be even more short staffed. What is some advice I could give her?