How am I meant to know I’m in arrears if the CSA says I don’t owe anything?

I have £35,000 debt with the csa apparently I was ment to be paying from 2002 to 2007 £77.80 per week I wasn’t aware of this as I never got sent letters asking me to pay.

I have however found letter’s saying each year wichi have found and sent photo copies to the csa each year states debt £0 balance £0 so how the hell am I ment to know I have to pay this money.

I have lost jobs to depression and stress now they are telling well sorry it might not say on some letters what you owe but you owe it well if I have to ill go to prison until they cancel this debt.