I do recommend calling the police. And if that doesn't work then after that, get stern with them. Don't threaten them, but show some authority that you're not gonna take it anymore.
I had some kid around 12 call me names the other day and he didn't want to stop and kept smiling about it until I got out my truck and used a stern voice and confronted him.
He finally realized I was serious and took off.
I'm 28 going on 29 and I'm not gonna be bullied by a 12 or 13 year old kid.
I was bullied in school and I didn't take it then and I'm not gonna take it now.
They think it's cool to bully someone and call then bad names, and taunt them. But it's not.