22.14 I paid in the store and I was shown the message “Declined” (rejected) on the card reader, but I saw the message "Done" with a checkmark on the phone. Did the transaction take place?

Even if the transaction was unsuccessful, the user will see a checkmark on the phone with the message "Done". If the card reader indicates that the transaction failed, try again. You can see whether the payment was made in the list of recent transactions.