You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I am Andrew Williams. Owing to an emergency, I want to change my existing reservation. So please help me in changing the reservation.

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: Sorry, there was no reservation found with your name.

USER: Not an issue. Thank you.

ASSISTANT: Thank you for opting us.