You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: Can you please help in chainging my existing reservation?

ASSISTANT: Sure, may I know your name?

USER: I have reserved my flight ticket in the name of Nicholas Green.

ASSISTANT: Give me a minute.

USER: Ok.

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

USER: Ok, not an issue. Thank you for your time.

ASSISTANT: Thank you reaching us.