I took a samsung galaxy note 4 with a broken scree...

I took a samsung galaxy note 4 with a broken screen. He fixed it for 200$. 1 week later, a big dot on the screen started showing up. I took it back to him to take a look at it. He accused me of breaking the screen although I had it in an Otterbox case and was extremely gente using it. I took it to another store and they told me the guy who installed the screen messed up. Unfortunately I couldn't find the receipt to have enough evidence to report him. What a scammer.