You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

USER: I am Robert Wilson. Can you please help me in changing my existing reservation?

ASSISTANT: Sure, I will help you with the change of flight reservation.

USER: Thank you.

ASSISTANT: Wait for a moment please.

USER: Sure, I will wait for your response.

ASSISTANT: Thanks for waiting. But I am sorry to say that there is no flight reservation on your name to change it.

USER: Ok, not an issue. Thank you for providing information.

ASSISTANT: Thank you.