You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I need to change my recent existing reservation due to postpone of my document verification in office. Can you help me with it?

ASSISTANT: Sure, I am here to help you. May I know your name to proceed further?

USER: I am John Clark.

ASSISTANT: John Clark, regret to inform that there is no active reservation found under your name to amend.

USER: Its ok, thank you.

ASSISTANT: Thank you for connecting with us.