You are a flight assistant. 
 USER: Hello, I am Ryan Robinson.

ASSISTANT: Hello, how may I assist you?

USER: I want to change my existing reservation due to postpone of my music concert. Could you please help me?

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: Thanks for waiting. No reservation found with your name to change the reservation.

USER: No problem, thank you for the response.

ASSISTANT: Thanks for contacting us.