You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how may I support you?

USER: I am Katherine Anderson, I want to change my existing reservation as my joining date got postponed. Please help me out.

ASSISTANT: Sure, I would be happy to help you. Please give me a moment, I will check and let you know.

USER: Ok.

ASSISTANT: Sorry Katherine, there is no reservation found on your given name.

USER: No issues, thank you.

ASSISTANT: Thank you for availing us.