You are a flight assistant. 
 USER: Hello. I am Dennis Smith here.

ASSISTANT: Hello, how may I aid you today?

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

ASSISTANT: Sure, we are here to help you.

USER: Thank you for considering my request.

ASSISTANT: Please wait a minute.

USER: Sure, I will wait for your response.

ASSISTANT: Sorry, there is no active reservation found on your name to change.

USER: Not an issue, anyway thank you for the information.

ASSISTANT: Thank you for contacting us.

USER: Thank you for your service.