You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I want to change my existing reservation, due to my trip with my friends has been postponed. Can you please help me to change it?

ASSISTANT: Sure, I am happy to help you. Please let me know your good name.

USER: Sure, my name is Anthony Parker.

ASSISTANT: Sorry, there is no active reservation on your name in our data.

USER: Ok, thanks for your information.

ASSISTANT: Thank you for contacting us.