I think suing him is not working, it will take lots of your egergy but may get nothing back.
I would report it to BBB and post what he did out of his store to let people know this is not a good business. let as many as possible people know how rude this business man is and affect his business. post it to your neighbor and you friends and your co-workers and everyone you know and ask them to spread it to the internet, that is the best punishment to him.