The very same thing happened to me in EZE two years ago. Quite fortunately, they didn't manage to get my wallet and camera, just a daypack with an umbrella and a couple worthless thing...

This is a very frustrating experience, but I'm sure a concert at the Teatro Colón or a good restaurant will help make it just a bad memory. For your passport, there shouldn't be a problem getting a new one in time. The Canadian Embassy is open tomorrow.