IT has certainly been a costly oversight of the bosses who run the Calcutta Electric Supply Corporation (CESC). But for mismanagement, this once cash-rich R.P. Goenka corporation would never have landed in the hole it finds itself in. A state government-appointed one-man committee has discovered that CESC overcharged its nearly 15,00,000 consumers over Rs 120 crore, by levying excess fuel surcharge on monthly bills.