This is the code for Indiana. I agree with Andy, your state probably has a similar code.
Any owner, holder, or custodian of any mortgage or other recorded lien who fails, neglects, or refuses to release the debt after it has been fully paid within 15 days of receipt of a written demand, shall pay the mortgagor a sum not to exceed $500. The amount may be recovered by suit in any court of competent jurisdiction, together with costs and reasonable attorney’s fees. [Ind. Code 32-8-1-2.]
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The opinions expressed are mine and they are not to be taken as legal advice.