CSA confusion

[Asteria]

A friend pointed me in the direction of www.privateagreement.co.uk to help calculate the new CSA level payments for my DH. The website stated that the CSA is closing next year and any new claims will incur a charge for both the NRP and the RP both to set up and ongoing. I have tried to trawl through the various labyrinthine websites, but there seems to be little clear information for either parent to work out where they stand.

DH is reluctant to go via the CSA because it will delay payments to his children whilst being established, incur a charge to both parents and actually give her less as he currently pays well over the required amount. Sadly his ExW seems to judge DH by her own dishonest and manipulative standards so is insisting that DH goes via CSA - despite that meaning that they will both be paying a fee for the service and the children will ultimately suffer. Sadly she is too hell bent on "destroying" him to realise that she is cutting her nose off to spite her face!

Is there any way that DH can insist that they stick to the agreement that was part of their divorce?

It's up to the parent with care to make a claim so if she wants to go via the CSA, she'll need to apply herself. Don't know how this is affected by a divorce-related court order though but if he's paying her money direct, he needs to be able to prove it in case his ex claims she's not being paid. So maybe pay via a standing order with 'Maintenance payment to x' as the payee's details, so it shows up this way in his bank account. If he pays cash, she could say she's never received any money.