You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: Can you please help me to change my existing reservation?

ASSISTANT: Sure, we are happy to help you.

USER: Thank you.

ASSISTANT: Can I know your good name please?

USER: Please check my reservation on the name of Margaret Harris.

ASSISTANT: Please wait a minute.

USER: Sure, I will wait for your response.

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

USER: Ok, thanks for your response.

ASSISTANT: Thank you for approaching us.