You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Ryan White.

ASSISTANT: How may I render you today?

USER: I need to change my existing reservation, Can you please help me with that?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please hold on for while, I will check and revert to you.

USER: Sure.

ASSISTANT: Thanks for your time. But sorry to inform you that, your name is not found in the reservation list.

USER: Ok, no problem.

ASSISTANT: Thank You.

USER: Thanks for your information.