Contact
One person reads this. Replies usually take a day or two.
Writing about a purchase
Include your anonymous ID from the app: open More → Your ID and tap it to copy. It is the only way to find your purchase, because there is no account to look you up by. Refunds themselves are handled by Apple at reportaproblem.apple.com.
A rule that does not match your table
House rules vary, and that is not a bug — but a pad that cannot be made to fit your table is. Tell us the game, the country you play it in, and what should have happened. That is how the snooker red count and the cricket cut-throat mode got in.
A game we do not have yet
Name the game and roughly how it is scored. Games played by a whole region with no decent pad get built first.
Reporting a problem
Useful things to include: your device, the iOS version, the app version and build (both at the bottom of More), which pad you were on, and what you tapped. Screenshots help more than descriptions.