They usually tell u via mail/or phone (if u called them).
Chances are kinda on the lower end. Western is on a rolling basis. And usually by March, more or less they would be done with their interviews. That means, most of the spots are already filled. Plus, people on the alternative list will probably have a slightly higher chance to get in.
Last year, I knew a few people who were on "Hold" (same situation as you). At the end, they didn't get an interview. But I know Western will update ur application if you have anything to add. Maybe see if they will allow u to send more letter of recs, or do a school tour. I remember one lady from the admissions told me they give favor to students who toured their campus (shows that you want to be there). Wish you luck. Hope you'll get in!
Did u apply to any other schools?