You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: I intend to change my existing reservation as my plan to meet my parents got postponed. Can you help me updating the reservation which was made on the name of Helen Nelson?

ASSISTANT: Sure, please wait a moment I will check the reservation list.

USER: Ok.

ASSISTANT: Thanks for waiting, unfortunately there is no reservation found by this name.

USER: It's ok, thank you for the response.

ASSISTANT: Thanks for approaching us.