A seed company prints on every packet: 'If this seed fails to sprout, we will replace the packet free of charge.' Which of the following, if it happened, would show that the company has not kept to what it printed?

The printed promise is triggered by a failure to sprout and promises a replacement free of charge. Charging half the price for that replacement is a plain breach of it. The promise says nothing about seed that sprouts or about packets lost before sowing, so refusing a second packet in either case breaks nothing; and handing over a free packet without demanding the empty one is more generous than the promise, not less.