My husband used SUPPORT KIDS.COM to bring in his ex-wife on her child support. But beware. There are a couple of things they don't tell you on their t.v. commericals.
1. They may say "no cost to you", but actually they get 33% of whatever they collect.
2. You sign a one year contract. If they can't find the person or they can't get any money out of them, they will let you out of the contract. Otherwise, you have to meet one of three criteria to be released from it.
A. The NCP is deceased.
B. No collections for like the last 6 months of the contract.
C. (I don't remember this last one! It's been a while.)
3. You have to fill out a bunch of paperwork and give them the names and address of family members they can contact to try to find the NCP.
Actually, this worked out well for us at first because the "enforcement specialist" called my husband's ex-wife and threatened her with a license suspension, jail time, seizure of property, etc. if she didn't start coughing up payments. Amazingly, after she had dodged paying my husband for 5 years, once she heard all that she changed her tune and started paying for a while. She eventually quit her job, the contract expired and now she once again gives my husband nothing for the kids. But.....since you ask abut other agencies.....that's my two cents.