If any one is getting 2 Mbps speed on MTNL's connection, that is definitly by mistake as the person controlling the speed forgot to set it on 256 kbps. You can not say that MTNL has increased speed on unlimited connections. Those who get low speed on limited connection must complain to the authorities concerned. If they live within 4-5 km from local exchange, they should get proper speed. By improving the line quality, you will get proper speed.