You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Myself Raymond Hall. I want to change my existing reservation because my exam has postponed, can you please help me for that?

ASSISTANT: Sure, I will help you.

USER: Thank you for your hand.

ASSISTANT: Sorry for inconvenience, there is no reservation found with your name to change the reservation.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for reaching us.

USER: Welcome.