You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?

USER: Due to sudden change in the dates of summit which was going to be held in the place where I suppose to visit, I want to do some changes in my existing reservation, can you please help me?

ASSISTANT: Sure, I can help you with that. May I know your name to proceed further?

USER: Raymond Brown.

ASSISTANT: Please allow me a moment to check the details for you.

USER: Ok.

ASSISTANT: Your patience is greatly appreciated. Raymond, there is no reservation found under your name.

USER: Thank you. That's ok.

ASSISTANT: You are welcome. Thank you for contacting us.

USER: Thank you again for your service.