Bro I'm not facing any such problem.... The problem could be in your LNB or STB or even in the wire (lnb to stb) .....write an email to tata sky and describe your problem...and also ask them to check every thing wire, stb, lnb and digicard also...they'll fix it immediately....If they unable to fix problem..then demand for everything new and re-installation
They have Checked Lnb, Stb, Wire, Dish, Dish Relocation also done Checked with 86 box and 74 also they even checked with new 65 cm dish and new digicard still not able to find the problem