You are a flight assistant. 
 USER: Hello, I am Sandra White.

ASSISTANT: Hello, how can I support you today?

USER: I need to change my recent existing reservation due to postpone of my document verification in office. Can you help me in this?

ASSISTANT: Sure, I can change your reservation right now.

USER: Thank you.

ASSISTANT: Please wait for a while, I will check the reservation list and revert to you.

USER: Sure.

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

USER: It's not really a problem. Thank you for your information.

ASSISTANT: Thanks for opting us.