DWP Claiming back dated incorrect overpayment due to data entry error, how to defend?

[Guest]

DWP are claiming an overpayment of £3918.49 from back in 2006 , I have consistently told them they're wrong, and they have never produced ANY evidence other than simply to state "our records show" and ignore my remonstrations . On 6th October 2006 I , as a separated , single parent of 5 , moved house to a shared property with my wife, having reconciled our differences , and at that time, made the relevant departments aware, and made claim for tax credits as appropriate at the time, ceasing the claim for Income support . At some point in the proceedings , someone in their data entry has confused 6/10/06 with 10/6/06 ... clearly since they've consistently refused to provide any documentary evidence, never mind a complete audit trail, I cannot be sure exactly where this cock up manifested itself , but I DO know what the dates were, and have contracts signed and dated from the time showing the point at which we moved back in together. Their Claim began in about 2009/2010 when out of the blue a letter arrived stating that we owed some £4k in over payments... which we strenuously denied at the time, with assistance from CAB , and were met with a brick wall of nothing but "we have evidence to show you were cohabiting from 10/06/06 " and they refused to divulge what evidence... we KNOW that there can be no such evidence , since we were not cohabiting , until 6/10/06 at which point we followed all the proper procedures for notification . They refused to cooperate with the CAB representative , but then simply went quiet.... and stopped responding. Since then, every couple of years, either a debt recovery firm or the DWP have pushed the same button, and we have responded again with our denial and pointed to the Date issue outlined above, and again demanded their evidence, always with no follow up from that point. until now..... this month I got a letter again, except Now they say they're simply going to attach my earnings....at anywhere up to 20 % , or possibly 40% if they think it's fraud.... No court order, no nothing and no apparent means to stop them or defend against it .... to use the vernacular WTF ??? How do I stop this ????? some bloody data entry glitch from back when they moved to using external contractors for such things..... could be about to bankrupt me ????