If the manufacturer fails to repair or correct a nonconformity after a reasonable number of attempts, the manufacturer shall, at the option of the purchaser, replace the motor vehicle with a comparable motor vehicle of equal value or accept return of the vehicle from the purchaser and refund to the purchaser the full purchase price or lease price, including all collateral charges, less a reasonable allowance for the purchaser's use of the vehicle not exceeding 10¢ per mile driven or 10% of the purchase price or lease price of the vehicle, whichever is less. Refunds shall be made to the purchaser and lienholder, if any, as their interests may appear. A reasonable allowance for use shall be that amount directly attributable to use by the purchaser prior to his first report of the nonconformity to the manufacturer. In the event the consumer elects a refund, payment shall be made within 30 days of such election. A consumer shall not be entitled to a refund or replacement if the nonconformity does not substantially impair the use, value or safety of the vehicle or the nonconformity is the result of abuse, neglect or modification or alteration of the motor vehicle by the purchaser.