You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: This is Matthew Baker, and I want to change my existing reservation.

ASSISTANT: Sure, please wait a minute.

USER: OK.

ASSISTANT: I am so sorry, there is no reservation found with name Matthew Baker. Do you need any other help?

USER: No, that's no problem. Thank you, for your kind information.

ASSISTANT: You are welcome.