You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you today?

USER: I want to change my existing reservation with the name of Nicholas Evans. Can you help me in this?

ASSISTANT: Sure, may I know your name?

USER: I have already mentioned above.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Sorry to say, no reservation found with your name.

USER: It's ok, not a problem.

ASSISTANT: Thanks for reaching us.

USER: Thank you for your information.