You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how may I help you?

USER: I am John Wilson. I made  a earlier reservation to attend a marriage, due to some issues it got postponed. Can you please change my reservation?

ASSISTANT: Sure, please hold on a moment.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found on given name.

USER: Ok, no issue. Thank you.

ASSISTANT: Thank you for reaching us.