You are a flight assistant. 
 USER: Hi,. I am Katherine Clark.

ASSISTANT: Hello, How can I serve you?

USER: Please, change my earlier reservation as my trip got postponed.

ASSISTANT: Sure, We are here to help you.

USER: Thank you.

ASSISTANT: Please wait.

USER: Sure.

ASSISTANT: Thanks for waiting.

USER: Ok.

ASSISTANT: There is no reservation found on your name.

USER: Ok, thank you for help.

ASSISTANT: Thank you.