How frustrating. The airlines offer a certain service at a certain price, then once you have bought their product, they switch it on you. In any other business, it is called bait and switch and highly frowned upon. I'm not sure why airlines are the exception.
This happened to me a few years ago, when Midwest Express was experiencing a transition/selling their airline. They switched my flight from a morning flight to an afternoon, with arrival at night. I found a flight with a different carrier that had even better times than the original flight. Then I told them I had plans that evening which absolutely could not be changed (dinner at Cindrella's Royal Table) and they agreed to give me a refund. A couple months later, still no refund on my credit card statement. So I called them and they had forgotten. Ugh! The refund was on the next statement.