You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello,.

USER: I am Larry Walker.

ASSISTANT: How may I help you today?

USER: Could you please change my existing reservation?

ASSISTANT: Sure, please be on hold.

USER: Ok.

ASSISTANT: Sorry, we did not find any reservation in your name.

USER: Fine, thanks for the information.

ASSISTANT: Thank you for your presence.