He got a call from CSA and just hurled abuse on me

My STBX got a call from the csa today, which resulted in calling me up and hurling abuse and names at me for being two-faced and trying to bleed him dry ...

He has not paid any maintenance for his children for a year and wants to dissolve everything between us = trying to get me to accept his ideas.

I am taking out a non molestation order against him now as it was the last straw in a long list of verbal abuse and inappropriate behaviour. I presume the csa will follow on his tracks now and even if it takes some time they will make him pay whatever he is due?

Yes the claim will start from the day you made the claim.

Of course he may try delaying tatics which may mean that you dont receive the money owed for some time.

MCR, I think the abuse is par for the course unfortunately when they don't like what they hear! My ex hasn't paid maintenance since we split which is nearly a year now apart from a paltry £40 received via the csa while he was on Jobseekers allowance (that equates to £5 per week for all 3 of his children). He's now working so I've told the CSA (of course he didnt inform them and is even trying to claim to being a fulltime student!!) - funny that, I phoned where I knew him to be working and they told me he was 'in a meeting' - not working my rse! So Im still waiting for my new assessment two months later and no doubt by the time it arrives he will have finished working! CSA move so slowly so expect a wait. They will backdate from the time you put in your claim as gettingadjusted says and as far as Im aware any arrears stay open until they are settled.
Good luck