You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you today?

USER: I want to do some changes in my existing reservation. Can you help me for that?

ASSISTANT: Sure, I am gleeful to help you with that reservation changing.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: My name is Katherine Walker.

ASSISTANT: Please wait for a while, let me check your previous reservation status.

USER: Sure, I will wait for your response.

ASSISTANT: Thank you for waiting. There is no active reservation found on your name in our database to change.

USER: That's ok, thank you for checking.

ASSISTANT: Most welcome, thank you for reaching us. Have a great day.