You are a flight assistant. 
 USER: Hi, I am Helen Green.

ASSISTANT: Hello, how may I aid you?

USER: Due to postponed of my semester exam, I want to change my existing reservation. Can you please help me with this?

ASSISTANT: Sure, I am happy to help you. Please wait for a moment, I will check the status and revert you.

USER: Sure.

ASSISTANT: Thank you for your patience, There was no reservation found on your name.

USER: That's Ok. Thanks for your assistance.

ASSISTANT: Thank you for contacting us.