(a) If a licensee or a person required to be licensed causes a producer, seller, or owner, or an agent of a producer, seller, or owner, to part with control or possession of all or any part of the person's perishable commodities and agrees by contract of purchase to pay the purchase price on demand following delivery, the licensee or person required to be licensed shall make payment immediately on demand.
(b) If a person makes demand for the purchase price in writing, the mailing of a registered letter that makes the demand and is addressed to the licensee or person required to be licensed at their business address is prima facie evidence that demand was made at the time the letter was mailed.
(c) If the producer, seller, owner, or agent waives the right to payment of purchase price on demand, the contract for the handling, purchase, or sale of the perishable commodities must be in writing. The parties shall prepare the contract in duplicate and set out in the contract the full details of the transaction. If the contract does not specify the time and manner of settlement, the licensee shall pay the full amount called for by the contract directly to the producer, seller, owner, or agent before the 31st day following the day of delivery of the perishable commodities into the licensee's control.