You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am William Green.

ASSISTANT: How can I help you at this moment?

USER: I would like to change my reservation, would it be possible to do?

ASSISTANT: I am here to help you, please wait for a minute to check the reservation details.

USER: Sure, take your time.

ASSISTANT: Based on your request, there is no reservation with your name.

USER: It's ok, no issues. Thanks for your information.

ASSISTANT: My pleasure, have a nice day.