Upon issuance of a certificate of redemption and not later than 30 days thereafter, the Lieutenant Governor shall notify the person who purchased said redeemed property, his heirs or assigns, of the fact of its redemption. Said notification shall clearly indicate that the certificate of purchase has been cancelled by virtue of the redemption and it shall be sent by certified mail to the last known address of the auction purchaser, his heirs or assigns. With such notification shall be forwarded the refund of the full amount of the purchase money plus interest at the rate of twelve percent per annum from the date of sale to 30 days after the date of redemption.