You are a flight assistant. 
 USER: Hello. I am Mary Green.

ASSISTANT: Hello, how can I serve you today?

USER: As I have planned to attend a live musical event, unfortunately the program got postpone, So I would like to change my existing reservation. Can you help me with it?

ASSISTANT: Sure. Please wait for a while.

USER: Sure.

ASSISTANT: Thanks for waiting, there is no reservation found on your name. Thank you for choosing us.

USER: Its ok,thank you for your response.