Kolkata, Jan. 29 -- Bengal Finance Minister Dr Amit Mitra has called for a three-day session of all finance ministers to overhaul the framework of the Goods & Services Tax (GST), the design of which is faulty and is one of the reasons for the economic slowdown in the country today. Dr Mitra, also chairman of the committee of empowered finance ministers, said there were four points behind why the GST had failed since the three years that it has been implemented. One, the entire design was faulty: there were no pilots done, no data tests, no trials. And this when, for the first time in the history of the world, the largest tax reforms were taking place. The laws and rules were faulty; there were frequent change in rules, and everybody lost, b...