Im trying to unlock a Samsung GT-S7500 , can anyone help please ?

i went on youtube and watched this video https://www.youtube.com/watch?v=-9bHdi2pGY4 and it seemed so easy but they failed to mention the fact you have to be registered and by registering it would cost £20 , im trying to open the FREE way if possible , or on the very cheap , its on virgin at the min and i want to use giff gaff in it , any help would be really appreciated

try galaxy sim unlock on play store