You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: I want to change existing reservation due to sudden postpone of my family trip dates. Can you help me with that?

ASSISTANT: Sure, may I know your name?

USER: I am Lisa Hernandez.

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

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

ASSISTANT: Thank you.