When did the agency initially make contact with you?

Did you ever supply income details to them?
if not your case maybe subjected to an interim assessment – in which case it can be changed into a proper assessment, this may decrease the amount they claim you owe.

Do you still have an on going regular maintenance liability for your 17 & 18 year olds?

If your circumstances have changed and you are earning less, send copies earnings info asap, this will prevent further arrears accruing at an inflated rate.

You should also request your Data Protection File and a complete account breakdown – there’s a template letter in the downloads section at http://www.afairercsaforall.co.uk – Your also welcome to join us in the forum.