You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: Actually my seminar is postponed so that I want to change an existing reservation, can you help me?

ASSISTANT: Yes, I am at your service. May I know your name to check is there any reservation done on your name?

USER: Sure, I am Margaret Edwards.

ASSISTANT: Edwards, there is no reservation on your name.So, I cannot change your reservation.

USER: Ok, no problem. Thank you for your help.

ASSISTANT: Thank you for your interest towards our service.