I thought I was paying but then my work went into administration

I was paying csa as normal by giroslips every week and all of a sudden there send me a letter saying there don’t except it like that no more and but a deduction of earnings order against me which mean there forse my employer to take money out of my wages.

This was going on for about 8 month then all of a sudden my former company I work for goes into administration which was bad enough then I get a call of csa saying there weren’t getting the money of my former employers and that I was a thousand pounds in debt.

I was fume in because I’ve got wage slips to prove money was taken of me every week but there say because there never received it . It was still my debt and that I ave to reclaim the money back of my former company administration which I’ve tried for 7 months only for them to say I can’t get it back cos there no funds available.

So il lost nearly a thousands pounds which I can’t get back and I’m in arrears with the csa ave u any advice for me on how I can sort this matter out do the csa take responsibility for the money I’ve lost?