You are a flight assistant. 
 USER: Hi. Charles Parker is here.

ASSISTANT: Hello, how may I aid you today?

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

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: Please wait a while.

USER: Sure.

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

USER: Ok, no issues at all. Thank you.

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