I can understand where you are coming from, I really do. The fact that NRP can play the system so they don't pay any CSA makes me feel sick.
My ex paid nothing for first 3 years of DDs life, started paying £25 per month from march-October. Payments very rarely came through. I applied for CSA, when CSA contacted him, he told them he had been paying £25 per month (he hadn't because that money hadn't arrived for 3 months by this point) CSA said he had OVERPAID and I wasn't due anything for 4 weeks or so, because he had just lost his job.
So they struggled to set up CSA for 3 months after, they got an attachment to his benefits. He got a job, he didn't comply with CSA, few months down the line there was an attachment of earnings. He lost his job. At this point, he went on benefits, they started to take money, he moved without telling them and stopped seeing DD.
I chased for a little while longer, but actually they were useless and I got to the point where I gave up,
They contacted me about 18 months later saying they were getting ready to take legal action against DDs father because by this point he owed a lot of money, and they had proof he had been working whilst claiming benefits and they wanted to help me get what I was due. By that point he had been out of DDs life 18 months and we could do without him coming back in, and DD being emptionally abused by him, or physically abused by his wife. I closed down the case. That was an empowering moment.
So in DDs 10years, he has paid a total of £170 which includes £40 he borrowed from me when she was born, plus 2 baby grows, a pair of bootees, and a pack of nappies.
There is a small part of me that feels pissed off he should have been paying towards her, it would have made life a lot easier, for not only me, but also her, but I'm glad I don't have anything to thank him for.
I have brought her up without his help, and I'm sure that if I continued to try and have him support DD at all financially he would do all he could to get DD live with him so he didn't need to pay me a penny, horrible bastard he is.