You are a flight assistant. 
 USER: Hi, I am Brian Martinez.

ASSISTANT: Hello, How can I help you?

USER: My grand mother retirement function got postponed, So I need to change my existing reservation.

ASSISTANT: Please wait a moment I will check and revert you back.

USER: OK,.

ASSISTANT: There is no reservation found with your name.

USER: OK, Thanks for your information.

ASSISTANT: Thank you for reaching us. Have a nice day.