You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you today?

USER: Due to some issues, I am willing to change my existing reservation. Can you please help me for this?

ASSISTANT: Sure, I am here to help you with that, can I know your good name to proceed further?

USER: Please check under the name Charles Clark.

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

USER: That's ok, thank you.

ASSISTANT: Thank you for reaching us.