You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How may I assist you?

USER: My name is Ruth Taylor. I would like to change may existing reservation. Can you please check if any reservation is found on this name?

ASSISTANT: Thanks for providing your name, Let me check the availability of the existing reservation with your name.

USER: Sure.

ASSISTANT: Sorry, We did not find any existing reservation with your specified name to change.

USER: OK. Thanks for your information.

ASSISTANT: Thank you for contacting us, Have a great day.