You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you?

USER: Can you please change my existing reservation?

ASSISTANT: Sure, may I know your name?

USER: Sure, My name is Gregory Phillips.

ASSISTANT: Ok, please wait for a moment.

USER: Sure.

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

USER: Oh! May be I have done a wrong reservation, Anyways thank you for the information.

ASSISTANT: Thank you for choosing us.