§ 405. Delivery of copy of contract or obligation; buyer's acknowledgment. The seller shall deliver to the buyer, or mail to him at his address shown on the contract or obligation, an executed copy thereof. Until the seller does so, a buyer who has not received the goods or services shall have an unconditional right to cancel the contract or obligation and to receive immediate refund of all payments made and redelivery of all goods traded-in to the seller on account of or in contemplation of the contract or obligation. Any acknowledgment by the buyer of delivery of a copy of the contract or obligation shall be printed or written in a size equal to at least ten point bold type and, if contained in the contract or obligation, shall also appear directly above the space reserved for the buyer's signature. The buyer's written acknowledgment, conforming to the requirements of this section, of delivery of a copy of a contract or obligation shall be presumptive evidence of such delivery and of compliance with this section and subdivision four of section four hundred two in any action or proceeding by or against an assignee of the contract or obligation without knowledge to the contrary when he purchases the contract or obligation.