This concept is wrong.
You need to pay 154 (incl tax) as NCF for initial 100 SD channels in which 25 DD channels are manadatory & the remaining 75 channels will be of your choice. If you'll select pay channels in those 75 channels slot then you need to pay their MRP + NCF. After selecting 75 channels, if you want more channels then you again need to buy slots by paying a NCF of 24 (incl tax) for 25 SD channels. You can select HD channels also but they'll take more slot i.e 1 HD channel will take space of 2 SD channels.