Our were 970 and they wanted payment over 12 months but I rang and told them I needed longer and they let us pay it back over 3 years at 25 per month which is manageable.
You could ask for longer to apy it back or appeal if you believe you don't owe it back . Tax credit system is a nightmare, you see so many threads on this forum and most of them are to do with tax credits.
Why in 2009 did they not ask us to start making payments then especially that we are now being asked for overpayments from 8 years ago? We work damn hard and it sickens me that our tax money is given to people that have no intention of ever working and who defraud the system and are never punished. Maybe I should try the Citizens Advice in the first instance?Ask for a breakdown of the overpayment as you have mislaid your previous tax credits provisional and final award notices from those years.