You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you today?

USER: I want to change my existing reservation due to some technical issues. Can you help me in doing that?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: May I know the name on which the ticket has been reserved formerly?

USER: Sure, Nancy Green here.

ASSISTANT: Ok, hold on for a moment. Let me check.

USER: Sure.

ASSISTANT: Sorry Nancy Green, there are no flights reserved on your given name formerly.

USER: Ok, no problem. Thank you for your quick response.

ASSISTANT: Welcome, thank you for choosing us. Have a great day.