Incredibly insensitive

I am a current employee at Amazon, and recently got into a car accident. I was given a doctors note excusing me from work for five days. There was no issue when I first gave them this note. I was forced to come back into work when I realized they were using my time off instead of excusing me and I only had enough hours for three days off and I also had another appointment coming up that would be during work hours that I could not reschedule. 

Upon speaking with HR, I was told I would have to clock in and work in order to not use up all of my hours, less than a week after the accident. My whole body was fatigued and set back my healing a day or two. 

This is not the only time amazon has been incredibly insensitive and stingy with hours; once they took 5 hours off of my time off for a 4 hour work day. When I asked HR, they said they couldn't do anything about it.