You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I serve you?

USER: I want to change my existing reservation, can you help me with that?

ASSISTANT: Sure, May I know your name?

USER: I am Samuel Campbell.

ASSISTANT: Please wait a second.

USER: Sure, I will wait for your response.

ASSISTANT: Sorry, No reservation found on your name.

USER: That's fine. Thank you for your information.

ASSISTANT: Thank you for choosing us.