You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I want to change my reservation as my plan to visit Houston city is postponed. Can you change my reservation?

ASSISTANT: Sure, may I know your good name please?

USER: My name is Benjamin Smith.

ASSISTANT: Pleas wait for a moment.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found on your name in our database to change.

USER: Ok, thank you for the details.

ASSISTANT: You are welcome.