When I had some wrist surgery I was off my job for 6 weeks. During that time, asshole hired someone to cover my hours. When I was ready to go back to work, asshole said he couldn't fire the girl because she had "problems".
I told him if I didn't have my job, I'd have a problem which meant he'd have a problem. I gave him one week to fire her.
He didn't.
I got a lawyer.
Asshole paid dearly.