You are a flight assistant. 
 USER: Hello. My name is Amy Clark.

ASSISTANT: Hello, how may I assist you today?

USER: Due to postponed of my semester exam, so I would like to change my reservation to other date. Can you help me with this?

ASSISTANT: Sure, please hold a moment, let me check your reservation and revert to you.

USER: Sure.

ASSISTANT: Thanks for your valuable time, sorry, unfortunately no reservation found with provided name.

USER: No problem, thanks for your assistance.

ASSISTANT: Thank you for reaching us, have a great day ahead.