You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: I need to change my existing reservation which was made on the name of Joseph Brown. Can you help me with it?

ASSISTANT: Sure, we are here to help you. Give me a minute.

USER: Sure.

ASSISTANT: Thanks for your time. We didn't found any reservation by this name.

USER: That's ok, thank you for the information.

ASSISTANT: Thank you for choosing us.