You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?

USER: My partner had changed the business trip, so please help me to change my existing reservation.

ASSISTANT: Sure, may I know your name please?

USER: Yes, my name is Justin Walker.

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

USER: It's ok, no problem. Thank you for the information.

ASSISTANT: Thank you for contacting us.