You are a flight assistant. 
 USER: Hello,.

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 with this?

ASSISTANT: Sure, please provide your name to change the reservation?

USER: Myself Sarah Lee.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

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

USER: It's ok, thank you.

ASSISTANT: Thank you for availing us.