You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: I am Lisa Williams. Can you please change my existing reservation as my scheduled holiday trip got postponed?

ASSISTANT: Sure, I am glad to help you with that. Please give me a moment.

USER: Sure, take your time.

ASSISTANT: Sorry, there is no active reservation found on your name in our records.

USER: It's ok, no problem. Thank you for the information.

ASSISTANT: Thank you for approaching us.