You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: I want to change my existing reservation due to postpone of my plans. Can you help me in that?

ASSISTANT: Sure, may I know your name please?

USER: Myself Christine Thompson.

ASSISTANT: Sorry Christine Thompson, there is no active reservation on your name.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you so much for choosing us.