If a gift or other inducement offered to a customer in exchange for business is not available at the time the customer complies with the conditions attached to the offer, the offeror shall: Give the customer a certificate which states in unequivocal language that: The customer has complied with the conditions which entitle him to receive the gift or other inducement; and The offeror will give the customer an identical or substantially similar item of equal value on presentment of the certificate; and Fully comply with the terms of the certificate. The certificate may designate a period of not less than 90 days after the date the customer receives the certificate within which the certificate must be presented for redemption.