You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello, what can I do for you?

USER: Please change my existing reservation.

ASSISTANT: Ok. May I know your name?

USER: My name is Brenda Williams.

ASSISTANT: Ok, wait a minute.

USER: Sure.

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

USER: Thanks.

ASSISTANT: Thank you for reaching us.