How do I get the amount of back child support corrected and why was I never given option to wave my rights though a no contact order was in place?

Kids we're taken on a weekend visit many years ago and not returned as planned. The father kept them and had a court order in place to where It was no contact with my children ever! I was never given option to wave my rights They simply took them and that was that. Many years later I was sent a child support arrears paper that stated I owed 9,998$ in back child support. That's where they started to attempt to collect support on my kids still with no rights to see them. I thought they somehow had already terminated my rights up unto that point. Apparently this was not the case. I'm now responsible for 39,000$ in arrears and am attempting to pay as they keep arresting me. I first feel I don't owe it as though I never signed over my rights I never had any. Secondly the amount they are requesting would be false if in fact I did owe it. How can I fix this mess?