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If the agency did nothing, then you can get all your money back. If the agency did some work and the work was adequate, then the agency is entitled to payment for the work done. You can get the court to order a refund of the rest.
Law enforcement will not care about this issue, unless the agency took your money and did absolutely nothing, and refuses to refund. If that's the case, it would be a crime.
You mean if you sue and get a judgment and then he still won't pay? Then, you will have to have the sheriff seize his bank account and take the funds via a writ of execution or garnishment.