I tried unlocking the boots but I can't find the different colour combination such as the one's that Dani Alves is wearing (White/Grey), All I can find is the Silver/Red ones which Cristiano Ronaldo wears. Anyone know how to get White/Grey boots ?

look in Keegan thread, ask there maybe he's got them in his filefront

Those are the only Mercurial boots you can unlock mate ;)

And there's also one type of Nike Laser boot you can unlock too (red/white)