You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I be of your service today?

USER: I would like to change my existing reservation due to postpone of my annual event. Can you please help me?

ASSISTANT: Ok, I can help you easily. Please provide your name to find your reservation and change it as per your request?

USER: I am Lisa Clark.

ASSISTANT: Sorry, we did not find any reservation on your name to change.

USER: No problem, thank you for the information.

ASSISTANT: Thanks for connecting with us, have a nice day.