AirPlay Cast charged me for an upgrade I did not want

On March 19, I downloaded AirPlay Cast from the App Store to my iPad. While looking at the app, I determined that I didn't need or want it, but somehow with a single accidental touch I ordered an Upgrade Premium for $19.99 plus $2.05 tax charged to my MasterCard (apparently tied to my account). I immediately deleted the app from my iPad and submitted a refund request. The next day, my request was denied as "Not eligible for a refund." I requested a review and got the same response. I reported a quality concern and have received no response to that. On April 2, I called Apple Support and spoke with Damandreet, who listened to my concern, put me on hold a couple times to check, and told me it was against Apple policy to issue me a refund. We were on the phone together for almost an hour.

I am very tech-savvy and very careful about evaluating and making purchases, so I don't even understand how this charge went through. I am also a generally satisfied Apple customer of several years. I feel, frankly, like the app stole from me, and an arbitrary Apple policy is blocking this case from proper consideration and resolution.

Have you, dear reader, run into a similar situation?