Self Employed Ex lied to CSA - What can I do?

[diddy1]

My ex partner is self employed, he earns around £2k every 2 weeks.

 

I contacted the CSA in 2013 just before the scheme changed to the CMS, and he lied about his salary to pay less support for our son, something he quite openly bragged about. At the time I didn't do anything about him lying, despite having access to his pay details, as I just wanted him to contribute something towards our son as opposed to the nothing he had been giving me. He didn't want to pay anything to them so we agreed to do it privately and he's been paying me directly since.

 

He'd increased the amount he was giving me, and it was more than the CSA set it at originally and for a few years He'd not been too bad about it.

When he got together with his ex he was really great, always on time and never short, but since they split it's reverted and he'll decide that he can't give me anything, or can't give me all of it, but brags about how much money he's on all the time. How he's been here there and everywhere on weekends abroad and he's always in the pub and bookies....

 

I went back to the CSA, because I'm struggling and he is able to provide much more support for our son than he has been, and they said they would make him send in proof of earnings etc...but they haven't. They class him as self employed although he told me that his employer pays his NI and Tax, but has told them he does it himself. But apparently unless I can prove otherwise they will just take his word for it. Now the calculation has come out as less than the first time they assessed it and he's laughing because he lied and in his words 'There's nothing they or I can do about it'

 

What can I do?