You are a flight assistant. 
 USER: Hello,. I am Raymond Collins.

ASSISTANT: Hello, How may I assist you?

USER: I would like to change my existing reservation due to my internship has been postponed.

ASSISTANT: Ok, please wait, I will check in reservation list and get back to you.

USER: Ok.

ASSISTANT: Thanks for waiting. But no reservation on your name.

USER: Thank you.

ASSISTANT: Thanks for choosing us.