You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I support you today?

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

ASSISTANT: Sure, may I know your name please?

USER: Paul Mitchell.

ASSISTANT: Wait a moment let me check the reservation list and know you the current status.

USER: Sure, I will be waiting for your response.

ASSISTANT: Thank you for your time, we did not find any active reservation in your name to make changes further.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for reaching us. Have a nice day ahead.