You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: Can you help me with that change my existing reservation?

ASSISTANT: Sure, I am glad to help you. Can I know your name to check with existing reservation?

USER: Sure, I am Benjamin Wilson.

ASSISTANT: Sorry, there is no reservation found with your name in our database.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for choosing us.