I feel for you, fortunately my ex has been really good in this department, i think because he knew i would threaten for him not to see Blake. I know its a harsh thing to do, but in his case he never really cared about Blake until Blake was old enough to do more things for himself.
I know in Australia you can contact the Child maintenance people and they can organise to have it taken out of the persons wage???
All the best its alot of money that he owes you and if you ask me he is a bit of a lousy father in that respect that he wont provide financially for his daughter
es