Hi rickman,
Don't know if this is of much use to you, but i have been trying for 5 years to sort out CSA with DD's dad, i've even given them his last 3 places of employment and they were abosolutely useless and i mean useless.
CSA take 15% of their net earnings and have done for the past year or so.
Anyway, to cut a long story short, i got fed up of being fobbed off by ex telling me that he would pay through CSA, but he never contacted them once
Last November, i seeked out advise from CAB and they advised that i see a family lawyer as would be entitled to legal aid.
After seeing the solicitor and telling her what happened, she contacted ex via letter asking for a legally binding amount to be paid each month that we both agreed on and if he did not contact within so many days, then by right i could take him to court regarding assess that he has with no financila contribution.
It did work, but like i say, circumstances could be very different, he now pays £100.00 per month, but that is no way near 15%.
Good luck
Butty.xxx