Landlords have the right to run their businesses how they see fit, unless he is breaking the law. Have you reported every incident to your landlord? Perhaps, you haven't been pestering the landlord enough. Keep reporting until he is so fed up, he will evict the neighbor. He has to be able to show a pattern in court, in order to get an order of eviction.
Certified Paralegal, with 25+ years' experience & with Landlord & Tenant law experience.