You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Brandon Brown.

ASSISTANT: How may I help you?

USER: Owing to an emergency, I want to change an existing reservation, so please help me in changing the reservation.

ASSISTANT: Please wait for a moment.

USER: Sure.

ASSISTANT: Sorry, there is no reservation matching with your name in our portal to make changes further.

USER: Not an issue.

ASSISTANT: Thank you for reaching us.

USER: Thank you.