I’m in arrears but I have no explanation

thank you in advance

my ex put in a claim on the 4 aug 2013..i received a fully comprehensive statment showing dates years etc of arrears..and a statement of recovery via attachment of earnings.

namely how much and for how long etc…i have just received correspondance..adding a further £4000 arrears..but no comprehensive statement as before to prove said arrears????

on last telephone conversation it was confirmed that a member of my ex partner works for the csa and im now in a “case sensitive” classification ..please advise post haste regards Neil