You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I'm Dorothy Parker here.

ASSISTANT: How may I assist you?

USER: I want to change my existing reservation, because of postpone of my business meeting. Can you please help me?

ASSISTANT: Sure, wait for a minute.

USER: Ok.

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

USER: Ok, that's fine.

ASSISTANT: Thank you for contacting us.

USER: Thank you for your kind information.