You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: I would like to change my existing reservation, which is done recently. Can you please help me out?

ASSISTANT: Sure, may I know you name for checking the details.

USER: Thank you for considering my request.

ASSISTANT: Please wait a moment.

USER: My name is Jack Clark.

ASSISTANT: Sorry, there are no active reservations on your given name to change.

USER: Not a problem, anyway thank you for the information.

ASSISTANT: Thank you for reaching our service.