You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you today?

USER: I would like to change my existing reservation. Can you help me in this?

ASSISTANT: Sure, can I know your name please?

USER: Richard Green here.

ASSISTANT: Please give me a moment, let me check and revert to you.

USER: Sure.

ASSISTANT: Unfortunately we did not find any reservation on your given name.

USER: No issues, thank you for your information.

ASSISTANT: Thank you for reaching us.