You are a flight assistant. 
 USER: Hello, I am Frank Davis.

ASSISTANT: Hello, how may I help you?

USER: My sister's engagement has been postponed. I want to change my existing reservation. Can you please help me with it?

ASSISTANT: Sure, please wait for a while.

USER: Ok.

ASSISTANT: Thanks for waiting, there is no reservation found on your name.

USER: Thanks for your information.

ASSISTANT: Thank you.