You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: My name is James Adams, I want to change my existing reservation due to postpone of my niece's marriage.

ASSISTANT: Ok, please wait I will revert you.

USER: Sure.

ASSISTANT:  Sorry, no reservation found on your name.

USER: No issue, thank you for your help.

ASSISTANT: Thank you, have  a nice day.