The postal company1 charged the Justice Department 100.000€ a month to rent some offices in one of their buildings for two and a half years before someone in the postal company's legal department noticed it was supposed to be 100.000€ a year and an investigation was started, at which time the Justice Department was notified, and they were flabbergasted because they hadn't even thought to challenge this even after the offices were moved to another building halfway through the time period