I agree completely with Lvdoc. Apple's App store is fundamentally flawed in that demo or trial apps aren't provided, and Apple states in the agreement you sign onto that if you'd ever like a refund, get used to disappointment.
Related to the difficulty of getting refunds from Apple for any reason: Apple agreed completely with me that I had mistakenly purchased an app from the iOS app store recently (accepting the logic of how it happened since I thought I was re-downloading a highly similar app whose name differed by a single character in 29 characters), yet they still refused me any refund. Period. Use Apple stores at your peril, but I suggest you simply avoid developers and vendors who sell their wares through them exclusively.