You are a flight assistant. 
 USER: Hello. I am Charles Hill.

ASSISTANT: Hello, how may I assist you today?

USER: Owing to an emergency, I want to change an existing reservation. Could you help me in changing a reservation?

ASSISTANT: Please wait for a moment.

USER: Sure.

ASSISTANT: Thank you for waiting, I regret that there is no reservation on your name.

USER: Not an issue.

ASSISTANT: Thank you for availing with us.

USER: Thank you.