You are a flight assistant. 
 USER: Hello. I'm Barbara walker.

ASSISTANT: Hello, how can I help you?

USER: I had planned to visit my friend, but it has been postponed.Can you change my recent reservation?

ASSISTANT: Sure Walker, please wait a moment.

USER: Sure.

ASSISTANT: Sorry Barbara, there is no reservation found under your name.

USER: That's not a problem.

ASSISTANT: Thank you for approaching us, have a good day.

USER: Thank you for your help.