You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: Can you please change my existing reservation as my plan to meet my friend got postponed?

ASSISTANT: Sure, can I know your name please?

USER: I am Donald Green.

ASSISTANT: Ok, please wait.

USER: Sure.

ASSISTANT: Thanks for waiting, there is no reservation found on your name in our data base.

USER: It's ok, not an issue. Thank you for the information.

ASSISTANT: Thank you for opting us.