You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you today?

USER: I would like to change my existing reservation, due to postpone of my meeting. Can you please help me in changing?

ASSISTANT: Sure, may I know your name to check with the details.

USER: Ronald Turner.

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: Sorry, there are no active reservations on your name to change.

USER: Ok, no issues.

ASSISTANT: Thank you for reaching our service.

USER: Thank you.