I think tatasky has made compulsory FTA pack which is shown under the name of DD + complimentary pack. This pack contains 100 sd channels with mandatory NCF of 153 rs. If we want to add further free channels then it will come under additional NCF slab. This is my understanding now after doing some trials.
It's ₹381.39 for me kept few sports channels, infotainment and kids and some regional channels. Haven't selected any mainstream channels like Star Plus, Zee TV, or Sony.
Tata Sky can not force subscribers to pay for FTA channel,just complain to Trai on twitter handle with screen shot of subscription page so that they will fall in line,they can force only mandatory 26 DD channels