Where the seller delivers to the buyer a quantity of goods less than he contracted to sell, the buyer may reject them, but if the buyer accepts or retains the goods so delivered, knowing that the seller is not going to perform the contract in full, he must pay for them at the contract rate. If, however, the buyer has used or disposed of the goods delivered before he knows that the seller is not going to perform his contract in full, the buyer shall not be liable for more than the fair value to him of the goods so received.
Where the seller delivers to the buyer a quantity of goods larger than he contracted to sell, the buyer may accept the goods included in the contract and reject the rest. If the buyer accepts the whole of the goods so delivered he must pay for them at the contract rate.
Where the seller delivers to the buyer the goods he contracted to sell mixed with goods of a different description not included in the contract, the buyer may accept the goods which are in accordance with the contract and reject the rest.
In the preceding two paragraphs, if the subject matter is indivisible, the buyer may reject the whole of the goods.
The provisions of this article are subject to any usage of trade, special agreement, or course of dealing between the parties. (n)