You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I best serve you today?

USER: I want to change my existing reservation in the name of William Gonzalez. Can you help me in this?

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: Thanks for waiting, no reservation found with your name to change.

USER: It's ok, not an issue,. Thank you for your information.

ASSISTANT: Thanks for opting us, have a nice day.