@smbarr888,
The child support I pay is set by a formula (which is part of state law in my State). You simply take your income, the other parents income and a few other things like childcare expenses and the percentage of time the child lives with each parent... and then you get a number.
There is an amount that the child support should be according to the rules, and the court is the referee who figures it out when there is a disagreement. If the correct amount is $170 a month and he was paying $800 a month, then yes... he was overpaying.
I did go through this process. I was paying (voluntarily) about twice what the formula said I should be paying. It was causing me hardship. When I figured out how much I should be paying, I went to the court and had a legal decision that I would pay the correct amount.
Both sides of this process should talk to a lawyer. And things are easier if you can make this a negotiation rather than a fight.