You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you at this moment?

USER: I am Gregory Walker. I want to make some changes in my flight reservation as my trip got postponed. Can you please help me?

ASSISTANT: Sure, I will help you. Please wait for a moment.

USER: Thank you. I will wait for your reply.

ASSISTANT: Sorry, there is no reservation existing on your name.

USER: Not an issue. Anyway, thank you for checking.

ASSISTANT: You are welcome, have a nice day.