Bro it's better u go for the dth change compare to airtel and tata play their are very less subscribers of d2h if their is issue in lnb u don't have any 2nd option rather then changing the equipment.
I searched on Google yesterday & solved query myself, but I expected d2h thread members to answer this , I posted query here ,first coz some guys have a deep study of respective DTH 's
Coz of little study I saved Rs. 130 coz price quoted to me was for dual LNBF