You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I give assistance to you?

USER: I am Sarah Walker, Due to an emergency I want to change my existing reservation.

ASSISTANT: Ok, please give me a minute.

USER: Sure.

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

USER: Not an issue. Thank you for your service.

ASSISTANT: Thank you, Have a nice day.