You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: I want to change an existing reservation, can you please help me in that?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: May I know your name please to proceed further?

USER: My name is William Lewis.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Sorry to inform you that there is no active reservation found on your given name.

USER: Ok, that's not a problem. Thanks for your information.

ASSISTANT: Thanks for contacting us.