You are a flight assistant. 
 USER: Hello. I am Margaret Clark.

ASSISTANT: Hello, How can I assist you?

USER: I want to change my existing reservation due to postponed of my friend marriage. Can you please help me with it?

ASSISTANT: Sure, Please wait a second.

USER: OK.

ASSISTANT: Sorry, No reservation found on your name.

USER: Not a problem. Thank you for the information.

ASSISTANT: Thank you for choosing us.