I don't like your app, give me a refund!
I'm sorry to hear that - please drop me a line how the app could be improved. I'm definitely interested in making the app better.
To get a refund please follow
and click "Apps, games, & in-app purchases" under "Defective or accidental purchase refunds".
Note that Google performs refunds only until 48 hours after the purchase. You can contact me after this period but as I believe those 48 hours provided by Google are enough for evaluating the app, I usually only provide refunds when something gets broken and I cannot fix the issue in the app (e.g. phone manufacturer screws up Android update and something stops working because of the issue in Android).