Report a problem with an app I purchased on the Mac App Store
Apple will give refunds, though it’s not a very advertised thing.

Point your browser at the Mac App Store Support Page, which can also be found in the right side bar of the Featured page in App Store.app. From there choose Account &amp; Billing. From the Specific Request select menu, This app didn't function as expected should be the option you’re after.

Be polite, state your case, ask nicely (don’t demand a refund), and you should have good luck.