Yes, you can. If you can prove to the agency that the people owe you money, and you don't mind losing a significant cut of it, they'll chase down the person for you.
Most of the time, the proof comes as a judgment in small claims court.
Note that if you win a case in small claims, all that means is that the court deems that the other party owes you money. It's up to you, not the court, to make sure that debt gets paid. That's where collections agents come in.