Ex lied to CSA saying I was the father

I met and married a woman who was 3 months pregnant at the time. I then was named father on birth certificate.

Mistake number 1.

When our marriage broke down she claimed csa by telling them i was the father. Fraud i hear you scream! I told csa i was not the father but was made to pay her £45 a week, this was paid cash through the door on her insistance.

Mistake number 2.

I paid for a dna test, set up with information from csa she would not comply and csa claimed they could not get involved.

Mistake number 3.

After a year long battle with solicitors and family court i finally got her to admit i am not the father and she was pregnant when we met. Great i hear you cry, not alas no this is the csa after all… after making this known to the csa i was told i could only claim back some off the £4938 owed to me even though she commited fraud. What, i cryed, you got to be joking. The csa then sent a letter stating i would get £2778 paid back into my account on the 12th july i would have thought quickly due to circumstances mistake 4 upon calling i was told i would only get £2,682 a £95 drop in 2 weeks and they say the are not a profit making company hummm and i can hear you all saying well your getting your money back but please bear in mind SHE LIED and committed fraud.

I am still trying to get money back from csa anyone with any ideas please help !!!