You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello, how may I help you?

USER: I want to change my existing reservation due to postpone of my document verification. Can you help me?

ASSISTANT: Sure, may I know your name?

USER: I am Donna Moore.

ASSISTANT: Please wait a minute.

USER: Ok.

ASSISTANT: Sorry, there is no reservation on your name in our database.

USER: Thanks for your kind response.

ASSISTANT: Thank you.