I have been paying csa for 19 years run into arrears twice but this was added to my monthly payments till clear. I recently found that i have been paying £2500 more than i should have. When i questioned this they said i owed them £9000 that they previously said they decided not to collect but they are reinstating this debt. Can they do this i know nothing about this debt or how it could happen . It is as if i did not question my over payment it would have been forgotten about.
I find it surprising that the CSA would chose not to collect a debt, especially of this size - it's out of character, to say the least. I would ask them for a breakdown of how the arrears have occurred, and I would also go and see your MP asap to raise a complaint about this.