You are a flight assistant. 
 USER: Hello. I'm Kathleen Roberts.

ASSISTANT: Hello, how may I assist you Kathleen?

USER: I had planned to go on a vacation, but it has been postponed.Can you change my existing reservation?

ASSISTANT: Sure, I can help you with that. Sorry, there is no previous reservation found on your name.

USER: Ok, that's not a problem.

ASSISTANT: Thank you for contacting us.

USER: Thank you for your help.