AINT CSA BEEN DITCHED ?

csa take 30% of the fathers income, if the women is on the ponce she will get 20 quid and the rest of it goes towards her housing benifit/council tax and her income support so what happens is daddy dont get the cash to spend on hes kid due to paying for hes ex to live,,,, which dont make a difference who left who and the mum ALWAYS gets custody, that makes it a fair system dont it ????