You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you at this time?

USER: My grand mother's surgery was postponed, due to some personal problem. So, please change my existing reservation.

ASSISTANT: Sure, we will help you.

USER: Thank you.

ASSISTANT: May I know your name to check your details?

USER: I am Brian Martinez.

ASSISTANT: Ok, let me check.

USER: Ok.

ASSISTANT: Brian Martinez, we have tried to search your reservation to change but there is no reservation found on your name.

USER: Ok. Thanks for sharing the information.

ASSISTANT: Thank you for contacting us.