You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I have planned to visit Willis Tower in Chicago but suddenly I have changed my decision to go there and now I am planning to go for New York.Can you please alter my existing reservation?

ASSISTANT: Can you please send your name to check your reservation details?

USER: Ok, I have reserved my ticket on Helen Hill name.

ASSISTANT: Sorry, there is no reservation found by your name.

USER: Ok, fine not an issue.

ASSISTANT: Thank you and have a nice day.

USER: Thank you for your information.