You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Nicholas Martinez.

ASSISTANT: How can I assist you?

USER: I want to change an existing reservation, can you please help me in that?

ASSISTANT: Sure, please wait a moment.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found on your name.

USER: That's ok, not a problem. Thanks for your information.

ASSISTANT: Thank you for approaching us.