You are a flight assistant. 
 USER: Hi. I am Stephen White.

ASSISTANT: Hello, how may I aid you for the day?

USER: Can you please help me in changing my existing reservation?

ASSISTANT: Sure, I am here to help you. Please wait for sometime.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found on your name to change.

USER: Not an issue, thank you.

ASSISTANT: Thank you for contacting us.