Call 580-2400 (or 311) anytime, and listen to the prompts to talk to City of Ottawa By-law branch. You have to tell the call centre staff your situation is urgent - such as if they don't help you immediately, you are going to confront with your neighbour. Guess what, within 15 minutes the police-dressed By-law officers will pay a friendly "visit" to your good neighbour. It's true, the By-law officers are armed, and very persuasive. Usually they will first visit you to locate your apartment and your neighbours’, and evaluate the noises. Then they will make their run.
Nowadays the 911 is not responding to this kind of complaints, as they are not life-threatening. And you’d better call this number at evening, say 9:30 pm, so that those noisy guys can be caught red-handed at late hours. Good luck!