You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I amend you?

USER: Robert Parker here. Please change my existing reservation to new dates.

ASSISTANT: Ok. I am here to help you.

USER: Thank you.

ASSISTANT: Please wait for a while.

USER: Sure, take your time.

ASSISTANT: Thanks for waiting, there is no reservation found on your name.

USER: It's ok, thanks for your information.

ASSISTANT: Thank you for opting us.