Section 12H. As used in this section the following words, unless the context requires otherwise, shall have the following meanings:—
''Charge card'', any card, plate, coupon book, or other single device existing for the purpose of being used from time to time upon presentation to obtain goods or services and which is issued pursuant to a charge card agreement.
''Card issuer'', any person who issues a charge card pursuant to a charge card agreement, or the agent of such person with respect to such card.
''Cardholder'', any person to whom a charge card is issued or any person who has agreed with the card issuer to pay obligations arising from the issuance of a charge card to another person.
''Charge card agreement'', an agreement signed by a person in the commonwealth pursuant to which such person may obtain goods or services upon presentation of a charge card from time to time and under the terms of which no finance charge may be assessed and the payment for such goods or services is due in full upon receipt of a monthly statement.
No card issuer under a charge card agreement may assess a delinquency charge, late charge or similar charge upon a cardholder which shall exceed one and one-half per cent per month computed upon an unpaid balance; provided, however, that no such charge shall be assessed on an unpaid balance until such balance has been outstanding for a period of not less than ninety days after written notice of such balance has been sent in a monthly statement mailed or delivered to the cardholder.
A card issuer, whether located within or without the commonwealth, may assess an annual fee provided that the cardholder is notified of the amount of any such fee on or with the billing statement for the billing period prior to that in which the annual fee is billed to the cardholder's account. A cardholder may cancel his charge card agreement at any time during this period without penalty. If the cardholder cancels the agreement at any other time during the year, he shall receive a refund on a pro-rata basis of two-thirds of the annual fee; provided, however, that for the purposes of this section a cancellation is not effective until the cardholder pays in full any outstanding balance.