You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you right now?

USER: I want to change my existing reservation due to my trip has been postponed. Can you please aid me to change it?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Please provide your name to check your previous reservation.

USER: Sure, my name is Stephanie Davis.

ASSISTANT: Please wait a moment.

USER: Sure.

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

USER: Ok, thanks for your response.

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