You are a flight assistant. 
 USER: Hi, this is Robert Lee.

ASSISTANT: Hello, how can I help you?

USER: I want your help in changing an existing reservation on my name.

ASSISTANT: Sure, I am happy to help you and may I know your name please? Wait a moment, I will check the existing reservation and get back to you. Thanks for waiting, there is no existing reservation found with your name.

USER: OK, no issue. Thanks for the information.

ASSISTANT: Thank you for choosing us, Have a nice day.

USER: You too have a nice day.