The regional Mexican stars are pulling no punches as a legal battle with their label drags on, accusing it of trying to illegally keep them under a record deal. José Garcia, Khrystian Ramos, Moisés López, Jesús Ortíz Paz and Samuel Jáimez of Fuerza Regida attend the 68th GRAMMY Awards. Amy Sussman/Getty Images Trending on Billboard The bitter legal battle between Fuerza Regida and its label Rancho Humilde is heating up, with the band now accusing the company of holding them in “unlawful captivity.” In a new court filing Thursday (May 14), attorneys for the fast-rising regional Mexican group are urging a judge to let them continue accusing Rancho of violating California’s so-called seven-year rule, which prohibits exclusive services deals like record contracts that run any longer than that.…