You are a flight assistant. 
 USER: Hello. I'm Rebecca young.

ASSISTANT: Hello, how can I guide you Rebecca?

USER: I had planned to visit my family, but it was postponed.can you change my existing reservation?

ASSISTANT: Sure, just wait for a minute.

USER: Ok.

ASSISTANT: Sorry, there is no previous reservation matching with your name.

USER: Ok, that's not a problem.

ASSISTANT: Thank you for your positive response.

USER: Thank you for your help.