Guile returns this problem when the appointment does not have a failed saved-card payment that the customer can retry. Paid, externally settled, canceled, rejected, expired, and no-show appointments cannot use this operation.
{ "type": "https://docs.guile.app/problems/appointmentPaymentNotSettleable", "title": "Appointment Payment Not Settleable", "status": 409, "detail": "This appointment does not have a failed payment that can be retried."}
