You are a flight assistant. 
 USER: Hello. My name is James Mitchell.

ASSISTANT: Hello, how may I assist you?

USER: I would like to change my existing reservation, could you help me out?

ASSISTANT: Sure, please wait for a while.

USER: Sure, take your time.

ASSISTANT: Sorry, there is no reservation found on your name in our data base to change.

USER: That's ok. Thank you for your time.

ASSISTANT: You are welcome.