You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you? We are from Central  Travel agency.

USER: Actually my trip got postponed so that I want to change my existing reservation, can you help me?

ASSISTANT: May I know your name please, to check is there any reservation is there or not on your name.

USER: Sure, I am Melissa Nelson.

ASSISTANT: There is no reservation on your name, Melissa Nelson.

USER: Ok, no problem.

ASSISTANT: Thanks for contacting us.

USER: Thank you for your information.