As of March 21 when I saved this from their website, their policy was that the customer is entitled to a refund for a schedule change of more than 3 hours. I'm unable to find it on their website now (undoubtedly they took it down to avoid paying refunds) but I saved it as a PDF to protect myself when I saw the airlines were getting sketchy about providing refunds.

I would call back and insist on a refund based on the policy on their website. If they won't budge, dispute the charge with your credit card and file a complaint with the DOT (if they're still in business).