Back child support

A) you’re dealing with a state agency.
B) that agency happens to be child support.
C) that state agency happens to be in North Carolina.

Has anyone out there ever heard of or know why the child support enforcement agency in Raleigh would hold a child support payment. My ex sent $1000.00 last Tuesday to Raleigh and I called and they said that they have received the payment of $1000.00 however, it was froze in the account??? I told them as little times he does pay and now he sends a lump sum check and they wanted to hold it. I told them I needed the money to pay daycare and such bills and they have stated that I need to contact my local case worker. Well I have tried with no luck. Please help!!!