CARSON CITY — The Nevada Gaming Control Board has filed a complaint against CG Technology, which runs seven Las Vegas-area sports books, for underpaying about $700,000 on more than 20,000 winning bets. The complaint, filed Monday, also says about $100,000 was overpaid on more than 11,000 parlay wagers over a period of more than three years. The complaint alleges CG Technology initially tried to block the state’s investigation into the incorrect payments. The company conducts sports and horse racing betting at the M Resort, Hard Rock, Tropicana, Cosmopolitan, Silverton, Venetian and Palms. Winners who complained they were underpaid were given their full payment. But the complaint says the books never tried to make good on the underpayments to thousands of bettors who did not complain.