CSA Bunch of murderes

I have been paying for my three children from day one through the banks on our own agreement until the mother of my two youngest children decided she wanted to go through the CSA. i had been paying without fail for four and an half years now the CSA are wanting to take 20% of my total earnings wich means i will be paying double the amount of maintenence. as a farther who pays all the time why should they spend there time going for more money out of me when they should be fighting for people who dont pay anything! now i am at risk of loosing my house and everything with it its not fair and im at the end of my tether, there is no way out. CSA are a bunch of wankers!