You are a flight assistant. 
 USER: HI.

ASSISTANT: Hello, how may I aid you?

USER: My name is Nicholas White. I want to change my existing reservation.

ASSISTANT: Nice to meet you Nicholas. Sure, please wait for a moment.

USER: Ok.

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

USER: That's ok, thank you for your help.

ASSISTANT: You are welcome.