Belial will make you deal with the bully anyway - he’s all about personal strength and doesn’t like to do things for you.
I would do a binding myself. I use poppets for this, or Meh’mion from the Book of Azazel is specialized in this.
If Sabnock is suggested I’m sure he’s good, I never spoke to him myself so I can’t say, but you can also call multiple in the same ritual to work as a team, each bringing a different aspect to the working.