(a) This section does not apply to a retail installment contract in which the time price differential is computed using the true daily earnings method.
(b) If a retail buyer prepays a retail installment contract in full or if the holder of the contract demands payment of the unpaid balance of the contract in full before the contract’s final installment is due and the time price differential is computed using the precomputed earnings method or the scheduled installment earnings method, the buyer is entitled to receive a refund credit as provided by § 353.120 or 353.121, as applicable.