Ohio Revised Code Title XIII. Commercial Transactions § 1317.08

(B) In order for a retail buyer, or any of the persons described in division (A)(1) of this section that is liable on the retail buyer's obligation, to avail the retail buyer or other person of this section, the retail buyer or other person must prove that the retail seller or the holder of the retail installment contract has been notified in writing of the overcharge and has failed within ten days of such notification to advise the retail buyer of a full credit, or the retail buyer or other person must prove that the overcharge has been willful.  A correction of any overcharge within sixty days of the date of making of the retail installment contract is conclusive proof of lack of willfulness.

(C) This section applies to cases in which recovery is sought from the retail seller or holder of the retail installment contract.

(D) If charges greater in amount than those provided for in sections 1317.01 to 1317.11 of the Revised Code are contracted for or received by the retail seller or the retail seller's agent, assignee, or successor in interest, the retail buyer or the retail buyer's assignee or successor in interest may recover the total amount of finance charges paid to the retail seller or the retail seller's agent, assignee, or successor in interest, in excess of the interest rate that otherwise would apply under section 1343.01 of the Revised Code.