Email vadapalas.zigmas@gmail.com. One person reads it, usually within a day or two.
Tap the undo key, bottom left of the keypad. It takes back the last visit, even one that won a leg, and you type it again. Undo goes back as far as the start of the match.
On a double out a visit busts if it scores more than is left, or leaves 1, because 1 cannot be finished on a double. The score goes back to what it was before the visit and the three darts still count in the average, as in a real match. Straight out lets you finish on any segment and leave 1.
Three darts cannot finish on 169, 168, 166, 165, 163, 162 or 159 on a double out, and no visit can score 163, 166, 169, 172, 173, 175, 176, 178 or 179. Tonzo says so instead of accepting a score that cannot have happened.
When the finish could have taken fewer than three darts, Tonzo asks how many it took, so the averages are exact. You can switch the question off in Settings; each checkout then counts as three darts.
Tonzo uses the voices built into iOS. Better ones can be downloaded under Settings, Accessibility, Spoken Content, Voices. The caller can be switched off in Tonzo's Settings.
Settings, Restore Purchases, on any device signed in with the same Apple Account. With Family Sharing on, the people in your family group get Pro too. The purchase is handled by Apple; refunds are at reportaproblem.apple.com.
Every match is stored only on the device where it was played. There is no server copy, because there is no server. Deleting the app deletes them. Pro exports every match to a CSV file you can keep.