Hi again:
You could try your MP but I really can't see that it's within his/her remit to get involved in such matters.
Another contributor has slagged off the CAB because she obviously has had an unsatisfactory experience with them. However, you could find that your local CAB are more knowledgeable than the one referred to. After all, it's only advice they give, they're not there to solve personal problems.
Your b/f could also consider writing a detailed, unemotional letter to the CSA if he has difficulty contacting them by phone or speaking to them face to face? Better, too, if it was to be typed. Perhaps the CAB could give advice to this effect?
Plus, sending such a letter by recorded delivery to the CSA means that it has to be actually signed for, therefore they couldn't claim not to have received it. It might cost a few bob more to send it but it could be money well spent. And they'd be duty bound to give him a reply I would imagine.
Good luck.