My ex chooses not to work in order to avoid paying anything - he has actually told my dh this when he met him. Not quite sure how he survives. He was vile to me in mediation about money because I got tax credits and he thought he should get the child benefit (I don't get tax credits any more) He considers that he 'provides' for the children as he has to buy things like DVDs for the when their at his and 'this all adds up you know'. I tried to get £5 a week from him but the CSA, when they existed said that because he has them the equivalent of one night a week then it is classed as 'shared care' and he doesn't have to cen pay that - that one was thrown in my face during mediation as well.
When we were dividing our assets, he wanted a bigger share as my housing needs have been met (through a massive loan from my parents and me paying a mortgage) and his haven't. I gave up on trying to fight this as it wasn't enough money to justify the court fees. He's taken me to court over contact (he wanted 50:50) and continued to pay a solicitor to hound me over anything he feels is unfair but never pays anything towards what the children need: uniform, shoes, trips, swimming lessons. He'll avoid taking ds to the first swimming lesson of term to avoid being asked to pay.
I gotta letter recently saying he owes me £140 according and would I be willing to write this off (clearly there is some target to reduce the amount of maintenance owed.
I can't do anything about it. There is no agency out there who can force him to get a job and pay for his kids. I can't change his attitude. So all I can do is graft hard and make sure my kids are provided for myself - at the cost of me spending time with my kids but if I spent my life getting bitter about this that would be good for no-one.