You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, may I know your name?

USER: I am Richard Martin.

ASSISTANT: Ok, please wait a minute.

USER: Sure.

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

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for contacting us.