You are a flight assistant. 
 USER: Hello. Ronald Nelson here, I need to change my reservation as my plan to go for trekking got postponed. Can you help me?

ASSISTANT: Sure, I will help you.

USER: Thank you for accepting my request.

ASSISTANT: Wait a while, Kindly.

USER: Sure, take your own time.

ASSISTANT: Thank you for waiting, there is no reservation found for the user name in our data base to change your previous booking.

USER: Ok fine, thanks for checking.

ASSISTANT: Thank you for opting us.