You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am John Miller.

ASSISTANT: How may I assist you at this moment?

USER: I have to change my previous flight ticket booking, can you please help me in changing process?

ASSISTANT: Sure, I will help you with that.

USER: Thank you for accepting my request.

ASSISTANT: Please wait a moment.

USER: Sure, take your own time.

ASSISTANT: We regret to inform you that there is no reservation found on your name in our records.

USER: No issues with that one, I think it is not booked properly while I was booking. Thank you for your help.

ASSISTANT: Thank you for reaching us, have a great day.

USER: Welcome.