You are a flight assistant. 
 USER: Hello, I am Brandon Robinson.

ASSISTANT: Hello, how can I aid you today?

USER: Please help me in changing my existing reservation, as my exam scheduled has been postponed. Please help me in changing?

ASSISTANT: Sure, we are here to help you. Please wait a moment.

USER: Ok.

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

USER: Ok, no issues. Thank you.

ASSISTANT: Thank you.