You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I want to do some changes in my existing reservation. Can you help me for that?

ASSISTANT: Sure, can I know your name?

USER: My name is Justin Brown.

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

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for reaching us.