You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you?

USER: I am Sandra Scott, I want to change my recent reservation because program has been postponed, can you help me to change this reservation?

ASSISTANT: Please wait a while.

USER: Sure.

ASSISTANT: Sorry to say, there is no reservation on your name in our database.

USER: That's fine, thanks for your information.

ASSISTANT: Thank you for opting us.