You are a flight assistant. 
 USER: Hello, I am Timothy Mitchell.

ASSISTANT: Hello, How can I help you?

USER: My plan to visit a function is postponed I need to change my existing reservation.

ASSISTANT: Wait a minute I will let you know.

USER: Sure.

ASSISTANT: Sorry to tell that there is no flight reserved  on your name.

USER: Thank you.

ASSISTANT: Thank  you for contacting us.