Paid ex direct and she lied, so CSA wanted arrears I had already paid

I split with my ex 7 years ago when she walked out on me, within 3 months she had the CSA onto me whilst in the meantime tried to reduce the amount of time I saw the kids to as little as possible, I was then going through the Courts to obtain joint custody.

After 16 months I got joint custody & when I advised the CSA I was amazed to find out that I was still liable to pay although I had 50/50 custody, 1 week on, 1 week off, my ex had a good job earning £30k a year so not reliant on Benefits, so in the madness I decided I would have to submit my own claim against her & surprise surprise it took them 6 months to sort my claim out whilst hers was done in 2 weeks?????

I complained & was offered £120 payment for the case not being completed earlier, although I was entitled to over a £100 pm in CSA payments from my ex, I was paying my ex directly via cheque & 2 years down the line the CSA contacted me to say I hadnt paid them, I said I dont pay you I pay directly, they then said they had no notification of that, they contacted my ex who then stated she hadnt received any payments from me????

The CSA advised that if I couldnt prove that I had paid her they wanted back payments???? I then spent the next 3-5 weeks gathering all the information, bank statements etc to prove I had paid her, at the end of it there was a couple of payments short when I had paid her cash but couldnt prove but rather than get an apology or anything I got nothing, 6 months of absolute hell where my employers had been hounded for attachment of earning orders without justification, the stress & worry of knowing I had paid & that if I couldnt prove it would have to pay again!!!!

Then to top it off 5 years down the line after an fall out with my daughter orchastrated by my ex my daughter left my care & didnt return for nearly a year, in the meantime my ex claimed the child benefit for both kids & cancelled her CSA payments & then went back to the CSA for more money from me, convenient!!!!

To make out that she hadnt done this for money she ceased her claim for CSA, so she didnt pay me & I didnt pay her, fine, my daughter then returned & 3-4 months down the line she continues to claim the child benefit for both kids & this morning I received a letter from the CSA requesting my employers details & threatening that it is a criminal offence to fail to provide the details requested.

I rang them I advised that I was under the impression the case had been cancelled, they advised that it was not cancelled but couldnt confirm why I had received the letter & also they couldnt confirm they have had contact from my ex???? so why have I had the letter!!!!

They cause all the stress & worry even if your ex doesnt, they are a law unto themselves, can I sue them for harrassment?????? T

hey are a criminal organisation that destroy families & not work for the benefit of the children, the circumstances are irrelevent & the fact I have joint custody doesnt matter, she has the child benefit so she is entitled to claim from me if she wants to & I dont have a leg to stand on if she does,how can that be right?