(a) A registrant may make a guarantee which grants rights to the consumer in addition to those contained in General Business Law, section 798(12).

(b) In a rental of a hearing aid or sale thereof under an installment contact or other non-sale transaction covered under General Business Law, section 789(11), the cancellation fee shall be measured by the charge the registrant would make for a similar hearing aid and accessories sold outright to a customer. The cancellation fee shall be payable out of such sum the customer may have paid on account of the rental or purchase price and any security the customer may have deposited with the registrant. If the amount paid or deposited is insufficient to pay for the cancellation fee the registrant may be entitled to, the customer shall be required to pay the difference due in order to effect cancellation of the agreement. If such payments exceed the amount so due, the registrant shall return the difference to the customer forthwith.

(c) A contract of sale or rental may be utilized as the receipt and contain any guarantee.

(d) The registrant shall deliver to the purchaser a written statement setting forth the amount returned to the purchaser.

(e) A registrant may refuse to accept the return of a hearing aid within the 45-day guarantee period if the wear and tear on the hearing aid exceeds that which is reasonable. A registrant may not refuse to accept the return of a hearing aid for such reason unless the registrant provides a written statement to the customer which shall specifically describe the condition of the hearing aid upon which the registrant bases such refusal. A copy of such statement shall be placed in the customer's file. Within the 45-day guarantee period a registrant may not demand or receive from a customer the payment of any special or additional fee or charge for accepting the return of a hearing aid on the ground that the registrant has the right to refuse to accept the return by reason of unreasonable wear and tear on the instrument.