Article continues below advertisementVictoria Beckham is at the center of a fresh dispute inside the Spice Girls, with insiders claiming she has delivered a firm ultimatum to Geri Halliwell after weeks of frustration over the singer's refusal to sign on to a proposed Netflix documentary celebrating the group's 30th anniversary.The five-piece - Beckham, 50, Halliwell, 53, Melanie Brown, 50, Emma Bunton, 49, and Melanie Chisholm, 51 - have spent months planning a major anniversary year to mark three decades since "Wannabe" burst onto the charts.