Unfortunately the bully’s parents will not be held accountable, let alone the bully himself. The only way to deal with a bully is to inflict pain.
When I was in 6th grade a big fat 5th grader stole my bike and was riding it in front of me, taunting and laughing. I knew who he was, he knew who I was, he was gettin’ away with it only due to the fact I was smaller than him. I warned him, twice.
Then I jumped in the air to use my momentum and potential energy against him and kicked him off my bicycle. It worked better than I had planned. He started crying, he ran to his parents who simply weren’t listening when both he and I said he had stolen my bicycle and I warned him. I couldn’t figure it out at that time why they couldn’t see what was blatantly obvious.
Oh well, it became useful that around my school, kids knew that I stood up to him because he was known as a bully — even his brother in my grade had nothing to say.
Here's one solution...............
Physics!
Had a paper route when I was a kid and had one of the double bags that carried papers front/back and left it on the corner due to how heavy it was. Came back and it was gone. Neighborhood dick was across the street with it. Went over, punched him in the face, grabbed my bag and continued on my route. Never had another issue with him.