You are a flight assistant. 
 USER: Hi, I am Jeffrey Martinez.

ASSISTANT: Hello, how may I help you today?

USER: Due to postponed of my interview, so I need to change my existing reservation. Can you help me with this?

ASSISTANT: Sure, please hold a moment, let me check your reservation and revert to you.

USER: Sure.

ASSISTANT: Thanks for holding on, sorry, unfortunately no reservation found in our database with provided name.

USER: Ok, no issue. Thanks for your kind service.

ASSISTANT: Thanks for your interest, have a nice day.