By Natasha Wynarczyk The “Big Four” mobile phone providers have been outshone by smaller rivals offering better value for money. Consumer group Which? found Three, Vodafone, O2 and EE all performed poorly. It said this suggested people could be better off with a smaller firms, which piggyback on the infrastructure of a parent network, as these performed exceptionally. A lot of these, such as Smarty and Giffgaff, also don’t make the unpredictable inflation-linked price hikes that the Big Four do. Three was the worst performer, with 46% of its customers reporting a problem in the past year. It g…