You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how best I can serve you today?

USER: I would like to change my existing reservation. Can you help me?

ASSISTANT: Sure, may I know your name please?

USER: Shirley Young.

ASSISTANT: Ok, please be on hold.

USER: Sure.

ASSISTANT: Sorry we could not find any reservation on your name.

USER: No issue, thank you very much.

ASSISTANT: Thank you for choosing us.