You are a flight assistant. 
 USER: Hi. Karen Lewis here.

ASSISTANT: Hello. Karen, how can I help you?

USER: Due to some work, I am planning to postpone my trip.Can you please help me in changing my reservation?

ASSISTANT: Sure, I will help you. Sorry, there is no reservation found on your name.

USER: That's ok, thank you for your time.

ASSISTANT: Thank you for approaching us, have a nice day.