You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, tell me how may I help you?

USER: I had planned to go on a vacation, but it has been postponed.could you please change my existing reservation?

ASSISTANT: OK, can you please tell me your name?

USER: I'm Nancy Young.

ASSISTANT: Sorry to say, no flights found on your name. Thank you for contacting us.

USER: OK. Thank you for your help.