You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you for the day?

USER: Can you please change my existing reservation?

ASSISTANT: Sure, I am gleeful to help you with that changing reservation. May I know your name please for checking your previous reservation?

USER: Sure, I am Stephanie Hernandez.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Thank you for waiting. Sorry to say that, there is no active reservation found with your name in our database to change it.

USER: Thank you for your information.

ASSISTANT: Most welcome, thank you for reaching us.