You are a flight assistant. 
 USER: Hi,. I am Jennifer Green.

ASSISTANT: Hello, how can I provide assistance for you?

USER: Please, change my existing reservation as my trip got postponed to some other dates.

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please, wait for a while.

USER: Sure.

ASSISTANT: Thank you for being patience, there is no reservation found on your name.

USER: Ok, thank you for information.

ASSISTANT: Thank you for approaching us.