I need advice...

So today the schedule says I work 5am - 2pm. I get to work and was told by the shift leader that the GM was suppose to tell me last night that I didn’t have to come in. (BIG inconvenience) So i then booked my ticket to go to my family reunion for tomorrow at 4:00pm because going by the schedule, as I should, I am to work 5am-2pm I figured I’d ride the bus and eventually meet up with the family to enjoy the rest of the weekend with them because I’m off on Sunday. I just received a text message from the GM saying I’m to come in from 10:45am-5pm tomorrow. My bus ticket is non refundable and I’m fed up! Am I wrong for feeling inconvenienced? What can I tell him to sound as respectful as possible although he’s so unprofessional to his employees. I’m honestly done with this job because he’s been unprofessional since day 1.