You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you today?

USER: I already book a flight ticket to Denver from New York city to meet my uncle but due to my bad health my plan is postponed. Can you change my reservation with new dates?

ASSISTANT: Sure, I am here to help you. Can you please share your good name please?

USER: My name is Sandra Allen.

ASSISTANT: Please hold on.

USER: Sure.

ASSISTANT: Thank for being patient, there is no active reservation found on your name .

USER: Ok, thank you for the information.

ASSISTANT: Thank you for approaching us, have a nice day.