Rude manager. Pissed off employee!

Hello ladies, I am upset. I had to call out of work due to an appointment. My shift is 9-4 I called at 5:30 a.m spoke with the manager and he just flipped out on me (they're even lucky I called out 3 hrs before my shift) . He told me that if I knew about the appointment why didn't I get someone to cover my shift.? I told him I did look for someone to cover my shift but noone was willing to work. He said you should of let us know (It's not going to make any difference) I apologized and said I didn't know I had to let a manager know. Now, everytime someone calls out its fine there's no problem at all. My ob/gyn decided to call last week I scheduled the appointment for today (which was the only opening they had) I told the manager and he said " You do know it's not going to count as an excuse absent because you decided to call the day of the appointment" I told him "would it still count as an excuse absent if I bring in a doctors note" he said "no , now it's going to be a hassle looking for someone to cover your shift." When I first started working there (1 yr and 7 months ) the managers told me whenever I call out for an appointment it would count as an excuse absent. He decided to not put down as an excuse absent because his butthurt that I called out. In my opinion you can't do that just because you're pissed at the employee. My question is does a manager have the right to do that? P.s I work in Sams club and that's the same manager that told me I'm lucky I haven't gotten fired yet. Sams club is the WORST club ever!!! The managers are full of shit they favor employees and they are racist! As soon as home office comes to visit the store they act all friendly like everything is good and the store is looking "neat" because they know they can get in trouble. That asshole pissed me off. TIA