Pay-TV channels HBO, Showtime and Starz are blasting a much-ballyhooed study from a research firm that said all were losing subscribers to digital services such as Netflix, Hulu and Amazon Prime. The study from NPD Group released Monday said pay-TV channels had lost 6% of their subscribers in the last two years while online services had gained 4%. It received a lot of media attention including a story in the Los Angeles Times. “It’s clear that some consumers are trimming their premium-TV subscriptions,” Russ Crupnick, senior vice president of industry analysis for NPD Group, said of the study. But it’s not so clear to the nation’s three major pay channels, all of whom say they have grown their subscriber bases. “Showtime and every other premium network have increased both subscribers and penetrations over the last two years,” a Showtime spokesperson said, adding that the NPD study “does not accurately reflect actual subscriber counts.”