You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I want to change my existing reservation. Can you please help me in that?

ASSISTANT: Sure, may I know your name?

USER: George Collins here.

ASSISTANT: Ok, please wait for a moment.

USER: Sure.

ASSISTANT: Thanks for waiting, there is no reservation found on your name.

USER: Ok, no problem.

ASSISTANT: Thank you for choosing us.

USER: Thank you.