The schedule got changed over the weekend & I missed our shift

No labor schedule comes out on Thursdays.

I write down all of our shifts in a calendar on our telephone. I have been an employee at the marijuana dispensary for 18 weeks & I have never written down the wrong time or date in our schedule. The boss & the manager of the dispensary have changed the schedule on people a number of times. I assume that is what happened last weekend when I missed our shift on Thursday. I wrote down our schedule on the iphone calendar on Thursday & I was tied up to be off on Thursday & Thursday. I went out of neighborhood on Sunday when I finished our shift at the marijuana dispensary. One of our co-workers called myself and others on Thursday & left a message. I was hiking at the time & did not hear the message until much later that day. I was tied up to labor a shift & the locale was going crazy because I did not call or show up. I was particularly flabbergasted when I heard the news, because I wasn’t tied up to labor on that day. I double checked our schedule & it did not match what was written on the calendar at work. My boss threatened to give myself and others a written reprimand for missing work, & I showed his the schedule that I had written down in our iphone, however he told myself and others that I need to check the schedule more carefully next time. I assume they changed our schedule & I assume that is the reason why nobody wrote myself and others up for missing out on work. I do not like that they changed the schedule separate from telling anyone. It undoubtedly drives myself and others crazy.
Purple haze