You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Robert Hall.

ASSISTANT: How can I help you?

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

ASSISTANT: Sure, I will help you to change your reservation.

USER: Ok.

ASSISTANT: Please give me a moment.

USER: Sure.

ASSISTANT: Sorry, no reservation found on your name to change your reservation.

USER: Not an issue. Thank you.

ASSISTANT: Welcome, have a nice day. Thank you for choosing us.