31-1-242. Refunds on prepayment. Notwithstanding any other provision of law or terms of any retail installment contract to the contrary, any buyer may prepay in full, at any time before maturity, the debt of any retail installment contract and upon paying the debt must receive a refund credit for the anticipation of payments on a precomputed contract or for any other unearned fees calculated by use of the actuarial method. The refund amount is the portion of the original finance charge that is applicable to all fully unexpired months in the contract as originally scheduled or, if deferred, as deferred, following the date of prepayment.