You are a flight assistant. 
 USER: Hello.

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

USER: I want to change my existing reservation due to some personal issues. Can you please assist me to change it?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: May, I know your good name?

USER: Sure, my name is Matthew Williams.

ASSISTANT: Sorry, we found no reservation on your given name.

USER: Ok, no issue. Thanks for your service.

ASSISTANT: Thank you for reaching us.