CSA messing me about

I need some help, I have 2 on going cases with the CSA for my 2 daughters they have different fathers they both never wanted anything to do with there daughters. My eldest I applied for CSA not long after she was born, but only got the £5 per week off her dad through CSA as he apparently as a self employed farmer on his parents farm only earns £100 per week ( i seriously doubt that) anyway i got it re-assessed some years later when they upped it to £65 + £5 back payment (i actually thought this was excessive) my 2nd Daughter I only claimed last September (she was 5 then, basically i left it because i thought her dad would come round) we had to go through DNA tests etc it took them 6 months to finally get payment sorted for me (March/April 09) this one is £30 a week which is fine.

Then a couple of weeks ago i received a call from a very arragent csa worker to say that coz i had 2 cases and 1 was under the old rules that his one had to be brought up to date with the new rules (Which I understand) but my payments would be going down to £5 as it is only worked out under the NRP wage and not his partners, now i know he still lives with his parents so that did not apply before anyway.

I informed them about his working hours and that it was illegal for him to be working them hours on this supposed wage he’s told them. she said i had to rovide proof he was earning more than he said he was. Not sure how they expect you to do this but it wouldn’t be legal really would it!!! anyway i sort of took it as that and got on with it (you get to a point were you can’t be bothered fighting anymore) But then I recieved another letter saying that i Owed him £520 which he had over payed, (also in this letter they put my daughter down as having his surname which she as not????) as they had backdated the drop in the amount he has paid to September last Year??? I can’t understand them being able to do this without giving you some kind of warning it is happening!!

I thought the CSA were there to help the parent with care financially and get this from the father not make me pay him back for there blatent mistake! surely I should of been informed at the time about all this so i could of said well reduce my payments till i know whats happening! can you advise on this matter. I am also currently waiting to see my MP regarding this for further help as its just getting more and more distressing.