You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I help you?

USER: My name is Steven Hill, I want to change my existing reservation.

ASSISTANT: Can you please wait a minute I will check and revert back to you.

USER: Sure.

ASSISTANT: Thank you for being patient. we are sorry there is no reservation found by your name.

USER: OK, thank you for your confirmation.

ASSISTANT: Your welcome have a nice day.