There are too many variables to answer simply. Lots of details are left out, but most important is the state or nation of jurisdication.
In the USA many states set child support levels by a Statutory Formula set by the Legislature and/or the courts.
In a very common solution you could simply write a note or letter to the Court which handled the original case, and ask for a hearing...without a lawyer if necessary...to seek unfreezing of back funds, or to see if the father qualifies for work release with the court collecting the wages to forward to you. Good luck.