You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How exactly I can serve you the best today?

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

ASSISTANT: Sure, I am here to help you with that.

USER: Thank you for considering my request.

ASSISTANT: May I know your good name please to track the details?

USER: My name is Matthew Lee.

ASSISTANT: Ok, please wait for a while.

USER: Sure, I will wait.

ASSISTANT: We are sorry to say that, there is no active reservation found on your name.

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

ASSISTANT: Thanks for choosing us, wish you a great day.