You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

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

ASSISTANT: Sure, can I have your name to check with the details.

USER: My name is Stephen Carter.

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: Sorry, there are no active reservation on your given name to change.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for reaching our service.