Whenever, in any retail installment contract or retail charge account under this act, the retail seller, sales finance company or holder has knowingly charged, contracted for or received from the retail buyer any costs or charges not authorized by this act, all costs and charges in connection with such contract or account, other than for insurance authorized by this act, shall be void and unenforceable, and any such costs or charges other than for insurance authorized by this act shall be applied to the unpaid balance or, if the account has been fully paid, remitted to the retail buyer, and the retail buyer shall be entitled to recover all such costs or charges.
N.J.S. § 17:16C-54