child support i HAVE paid

I have been paying child support to my sons father for over a year. I have not collected recipts because he was on assistance and he did not want to claim it.Since he has custody, he would not let me see my son if i required a recipt.
In general my son lives with my parents. He has since he was 2 years old and i was not ready to raise a child so i signed that his father could have custody.
My parents recieve no money from my sons father at all. and they would like to go for full custody because it will be easier for me to have access to my son.
In the mean time the family responsibilty office has sent me a letter saying i owe a big amount in arrears. How can i leagally fight this and what steps do i need to take. Thank you

You could sign a sworn affidavit explaining what you have paid...and if they force the issue to go to court you will explain it to the judge as well

[reddogtt]

Try going to the judge and explaining the situation. Chances are, you will be required to pay the arrears. But look on the bright side. You may soon have greater access to your child.