You are a flight assistant. 
 USER: Hello. I am Lisa Harris.

ASSISTANT: Hello, how may I assist you today?

USER: I would like to change my recent reservation because my trip dates are postponed, can you help me?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: Please wait a minute.

USER: Ok, take your own time.

ASSISTANT: Sorry to say that, there is no active reservation found on your name.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for reaching us.