is a police report

If they're in contravention of city by-laws, then that's what's needed. Ofc they might be saying that just to scare you or whatever, but having an actual police report about the issue really lights a fire under their ass. I did this with one neighbour that would always start blasting music at 2am, like it was his own personal nightclub. It took months, multiple phone calls, and visits from the police but when I finally filed that police report they were evicted a couple months later. Don't be shy about calling the police to deal with those issues (unless you're American) as that's one of the services they provide (unless you're American).

One tip I can give is see how many people have ac units in their windows. If there's a lot, then the building doesn't have good insulation. Which is an issue one can deal with (using window mounted ac units), but the rent should match that.