You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you?

USER: I would like to change my existing reservation due to postpone of my seminar. Could you please help me?

ASSISTANT: Sure, I will help you. Please provide the name on which ticket was reserved.

USER: I am Janet Harris.

ASSISTANT: Sorry, there is no reservation existing on your given name in our records.

USER: No worries, thank you for the information.

ASSISTANT: You are welcome, have a nice day.