Pretty much the same thing happened to me on United. They cancelled my flight, put me on a different flight and said I didn't qualify for a refund because I paid the economy fare. After two phone calls and 45 minutes on hold total, I got my verbal confirmation of my refund. I had to wait 23 days to get the actual refund.
Original Direct Flight ($379)
Depart: Lihue, HI (7:25 p.m.)
Land: Denver, CO (6:12 a.m)
Total travel time: 6 hours and 47 minutes
Modified Flight (now with connection)
Depart: Lihue, HI (10:11 p.m.)
Land: San Francisco, CA (6:18 p.m.)
Lay-over (4 hours and 28 minutes)
Depart: San Francisco, CA (10:46 a.m.)
Land: Denver, CO (2:28 p.m.)
Total Travel Time: 12 hours and 17 minutes
The new flight was scheduled to land 8 hours and 16 minutes later than my original flight, so maybe that is why I eventually qualified for a refund. However, I was more concerned with the fact that it was originally a direct flight and was changed to a connection with a 4.5 hour lay-over. I could have paid $179 for a flight with a 2.5 hour lay-over in San Jose, CA on Southwest. Why would I pay an extra $200 for a shittier flight?