Trending @Capgemini; Why people in same role not having similar salary?

I am B1 with 5 years of experience and I see another B1 with 3 years of experience having more salary than me I have always got good rating Got 3 in first year Then always 2 rating for the rest 3 years But still having very low salary Joined as A3 then promoted to A4 then to A5 then to A1 So my performance has been consistently above average but still getting paid very low How can I get this fixed