Got a denial letter for unemployment, what now? - what worked for you?

I got a denial letter last week saying I left my job voluntarily, but I was let go as a sales associate. It has been weighing on me all week. The letter lists a deadline and a hearing process, but it is hard to follow. Did you bring documents or only talk?

Legal aid offices and some workforce centres help with unemployment hearings at no cost. A call is worth it.