I had a scheduled flight at 8:20 to JFK, but wanted to change the flight to 11:30 because of a very sick family member. I arrived at the airport at 7:30 am, asked the girl at check in if the flight was full and she said it was not, at 93%. I checked in, telling Ms Yung Ying Fung 3x that I wanted to change my flight to 11:30am. She gave me my pass. When I got to the gate they told me that she did not change my ticket number. I had to go back through the gate again and obviously missed the 11:30am flight. I spoke with the manager, Mr Li Kan who basically accused me of lying and had Ms Fung right there during the whole time, who laughed at me. Mr Kan also made me look for flights on my phone; he refused to change my flight even though they had told me that it was fine, and then told me if I wanted another flight I’d have to pay for it myself. The whole experience was humiliating & did not need to happen if Ms Fung did her job in the 1st place. If I was lying, why would I get to the airport 11 hours before my flight would leave? I called customer service and again the girl I spoke with did not get it. This is not hospitality, and I will never be using CEA again and will encourage others not to as well.