You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, which service are you looking for today?

USER: I am Katherine Lewis. I need to change my existing reservation due to postpone of my document verification in office. Can you please change my reservation?

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: Just give me a moment to check your details and I will revert to you.

USER: Sure.

ASSISTANT: Sorry to inform you that there is no reservation exist on your name.

USER: Ok, no issue. Thank you.

ASSISTANT: Thank you for consulting us.