You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you now?

USER: I have planned to change my reservation due to sudden change in my trip, can you assist me?

ASSISTANT: Sure, I am happy to help you with that. Can I have your good name please to check your reservation status?

USER: Donald Green.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Sorry Donald Green, no reservation has found under your name to change.

USER: No problem, thank you for searching.

ASSISTANT: Thank you for choosing us, have a good day.