You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Stephen Smith.

ASSISTANT: How can I help you today?

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

ASSISTANT: I am here to help you with that.

USER: Thank you.

ASSISTANT: Just give a moment.

USER: Sure.

ASSISTANT: Sorry, there is no reservation on your name in our database.

USER: That's ok, not an issue. Thanks for your information.

ASSISTANT: Thank you for reaching us.