You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I aid you for the day?

USER: I need to change my existing reservation owing to an emergency.

ASSISTANT: Ok. May I know your name to check the reservation?

USER: My name is Charles Clark.

ASSISTANT: Please wait a minute, I will check and get back to you.

USER: Sure.

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

USER: Thank you.

ASSISTANT: Thank you for contacting us.