You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I aid you today?

USER: I have planned to participate in Arts competition but due to some issues, I want to change my reservation.

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: May I know your name for checking your existing reservation?

USER: Sure, my name is Mark Baker.

ASSISTANT: Sorry to inform you that there is no reservation found under your name to change.

USER: No worries, thank you.

ASSISTANT: Thank you for opting us.