(a) As used in this Code section, the term:

(1) "Commercial insurance premium finance agreement" means any insurance premium finance agreement other than a consumer premium finance agreement.

(2) "Consumer insurance premium finance agreement" means an insurance premium finance agreement, as defined in Code Section 33-22-2, wherein the insurance contracts which are the subject of the premium finance agreement are for personal, family, or household purposes rather than business or professional purposes.

(b) A premium finance company shall not charge, contract for, receive, or collect a service charge other than as permitted by this chapter.

(c) The service charge shall be computed on the balance of the premiums due, after subtracting the down payment made by the insured in accordance with the premium finance agreement, from the effective date of the insurance coverage for which the premiums are being advanced, to and including the date when the final payment of the premium finance agreement is payable; provided, however, that service charges as specified in the premium finance agreement may continue to be charged until such agreement is paid in full.

(d) The service charge per consumer insurance premium finance agreement shall be a maximum of $12.00 per $100.00 per annum plus an additional charge which shall not exceed $20.00 per premium finance agreement, which additional charge need not be refunded upon prepayment. Any insured may prepay his or her premium finance agreement in full at any time before the due date of the final payment and in such event the unearned service charge shall be refunded in accordance with the Rule of 78 and shall represent at least as great a proportion of the service charge, if any, as the sum of the periodic balances after the month in which prepayment is made bears to the sum of all periodic balances under the schedule of payments in the agreement.

(e) The service charge for a commercial insurance premium finance agreement shall be properly agreed upon by the parties to the contract. The claim or defense of usury by such insureds who enter into such a commercial insurance premium finance agreement or their successors or anyone in their behalf shall not be valid if such agreement is a valid contract in all other respects.