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

ASSISTANT: Hello, how can I assist you?

USER: I want to change an existing reservation due to my exams got postponed. Can you please give me assistance?

ASSISTANT: Sure, please wait a moment.

USER: Ok.

ASSISTANT: Sorry there is no existing reservation found in your name.

USER: It's ok, not an issue. Thank you for your information.

ASSISTANT: Thank you.