Apparently she is protected by a recent greek law
We would like to inform you that the Greek government -faced with the unprecedented turn of events and following the example of other countries in the European Union such as France, Italy, Spain and Germany- passed a law that allows businesses in the travel industry to issue a credit note instead of extending an immediate refund in the case of cancellations of tourism services. This initiative was taken in order to protect both businesses and their customers, to ensure the viability of the tourism enterprises and secure the deposits of their clients. This aforementioned law is effective from February 25th2020 and applies to all services related to tourism, for business to customer (B2C) and for business to business (B2B) transactions. To issue a credit note in the form of a voucher, instead of a cash refund, is now common practice across the tourism industry, meaning that also we, as a business, will be receiving credit notes for any deposits we have made to our associates for future bookings.
pesonally I don’t think the credit card will reverse the charge
next alternative TripAdvisor