If the passenger had made the booking through any travel agency and the third party, in such case, the airline is not responsible for any cancelling or refund. You have to contact the same source for the cancellation.
Swiss Air cancellation policy says cancellation can only be made through the official ways that are provided by the airline.
If you have cancelled the flight because of any emergency problem, then in such a case, by providing the details, you can raise a request for compensation.