Fired for a bullshit reason

Have any of you been fired for a bullshit reason? I was let go yesterday from a part-time job that I've been at for roughly 7 months. Now I didn't care about the job, it has no relevance to what I want to do (it's a WFH data entry/customer support role) and is not even listed on my resume. Plus, I already have a role lined up after I graduate so I didn't need it anyway. But it really pissed me off. Maybe I was at fault to an extent, maybe I should have communicated better but it still felt like a bullshit reason to let me go. 

I get a call from one of the managers and she was all apologetic and told me that I was being let go because "I missed a shift which I was scheduled to work" I told her I had let my direct supervisor know my internet was down that whole week and I wasn't able to show up for any shifts. My direct supervisor told me it was fine and told me to send an email to the staffer to let her know and so I did. I thought I was covered on my end. Anyway, the internet comes back up I show up for my shifts, everything's good. The two main supervisors I work with, tell me I'm doing a great job and that my QA scores are great. I then get completely blindsided two days later with that call from the manager. She also mentioned that I missed another shift which was marked unexcused, I was sick and called out but couldn't get a doctor's note within 24hrs even though I did send one in later the next day. They told me not to worry about it. Lastly, she said I logged off early - I looked at the logs the earliest I logged off was 1:57 pm... my shift ends at 2 pm. That only happened a handful of times in 7 months. Technically yes, I did log off early so I guess she had a point there haha.

Turnover is very high at this company, there were 6 people in the training class with me in the first week, I'm the only one here now. Supervisors have an average tenure of less than 1.5 years. They are chronically understaffed and don't pay enough for the quality they expect. I don't know... maybe I shouldn't have logged off at 1:57 pm. I'm still pissed off because I was literally one of the best employees there, handled everything they told me to handle, and actually did try to do a good job and help out our customers. I feel it shows in the QA scores and what my supervisor thought of me, literally never had a comment from them suggesting this would happen.

Is this fair or am I just being a bitch?