My wife purchased two tickets on ET to fly from Dubai to SEZ, using her Mastercard. Between the time of purchase and the flight our Bank of America replaced our Mastercard because of a major fraud alert which affected thousands of accounts. When my wife and daughter tried to check in for their flight in Dubai they were refused because they did not have the EXACT card used to purchase the tickets. We explained that the cards were destroyed per bank instructions. The agent was presented with the new Mastercard with the same name as the original card and with her photo on the card. The Ethiopian Airlines agent would not accept that card and staunchly refused to discuss it any further. As the flight was boarding and my wife/daughter had a connection in the Seychelles and prepaid hotel rooms at an ultra expensive resort they were forced to purchase new tickets for an additional $1500 USD. My wife was Star Alliance Gold as well. This is a lesson for all to keep all old credit cards including those expired from the time of purchase until the time of the trip. Another lesson learned is we will never book another Ethiopian Airlines flight.