You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, may I know your name?

USER: I am Pamela Hall.

ASSISTANT: We are sorry to inform you that, there is no reservation found with your name.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you.