You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello,.

USER: I am Steven Lee.

ASSISTANT: How may I assist you?

USER: I need to change my existing reservation due to postpone of my conference. Could you please help me?

ASSISTANT: Sure, I am blissful to help you. Please wait a while.

USER:  Sure.

ASSISTANT: Thanks for your time. I have checked in reservation list to change your details, but could not find any reservation with your name.

USER: No problem, thank you for the information.

ASSISTANT: Thank you so much for opting us.