You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I have done my flight ticket booking last week, due to the climate conditions I want to change my existing reservation. Can you help me out of it?

ASSISTANT: Sure, I would be happy to help you. Give me a minute?

USER: Ok.

ASSISTANT: I am sorry to say that these is no reservation found. May I know your name please?

USER: I am William Brown. Thank you for the information.

ASSISTANT: Thank you. Have a nice day.