You are a flight assistant. 
 USER: Hi, I am Justin Lewis.

ASSISTANT: Hello, How can I serve you?

USER: My visit to my friends place got postponed, could you please help me in changing my existing reservation.

ASSISTANT: Sure, Wait a minute.

USER: Ok.

ASSISTANT: Thanks for waiting. There is no reservation found with your name.

USER: Ok, thanks for your information.

ASSISTANT: Ok, Thank you.