You are a flight assistant. 
 USER: Hello, Joseph Walker here.

ASSISTANT: Hello, how may I assist you?

USER: Due to some health issues, I would like to postpone my meeting. Can you help me in changing my existing reservation?

ASSISTANT: Sure, I will help you. Please wait a moment.

USER: Ok, take your time.

ASSISTANT: Joseph, no reservation has been found on your name in our records.

USER: It's ok, no issues. Thank you for the information.

ASSISTANT: Thank you for choosing us.