The holder of a home improvement installment contract or contracts may, upon agreement in writing with the buyer, refinance the payment of the unpaid time balance or balances of the contract or contracts by providing for a new schedule or schedules of installment payments. The holder may charge and contract for the payment of a refinance charge by the buyer and collect and receive the same, but such refinance charge shall be based upon the amount refinanced, plus any additional cost of insurance and of official fees incident to such refinancing, after the deduction of a refund credit in an amount equal to that to which the buyer would have been entitled under section 303¹ if he had prepaid in full his obligations under the contract or contracts, computed without allowance for any minimum earned finance charge. Such refinance charge shall not exceed the rate of finance charge provided under section 301 of this act.² Such agreement for refinancing may also provide for the payment by the buyer of the additional cost to the holder of the contract or contracts of premiums for continuing in force, until the maturity of the contract or contracts as refinanced, any insurance coverages provided therein. The refinancing agreement shall set forth the amount of the unpaid time balance or balances to be refinanced, the amount of any refund credit, the amount to be refinanced after the deduction of the refund credit, any additional premiums paid for insurance and of official fees to the buyer, the amount of the finance charge under the refinancing agreement, the new unpaid time balance or balances and the new schedule or schedules of installment payments. A refinancing agreement between a financing agency and a buyer may consolidate the new unpaid time balances of two or more home improvement installment contracts by providing for a new schedule of consolidated installment payments, and may provide for the acceleration of the consolidated time balance upon a failure of the buyer to pay in full any consolidated installment payment. A contractor may not consolidate two or more home improvement installment contracts except to the extent provided in sections 306, 307 and 308 hereof.³