You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I aid you today?

USER: Can you please help me in changing my existing reservation, as my exam got postponed.

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: May I know on whose name the ticket has been reserved formerly?

USER: I made the reservation on the name of Brandon Lee.

ASSISTANT: Sorry Brandon Lee, there are no flights reserved on your given name formerly.

USER: Ok, no issues. Thank you for your help.

ASSISTANT: Welcome, thank you for choosing us. Have a great day.