I've had this same thing -- wrong item -- happen at three companies, and each time, they have sent me a replacement free of charge. P&C, 4noggins and SPC.
Having worked in fulfillment for a short while, I think these kind of errors are near unavoidable. After you fill 15 orders, all the items start to look the same and even reading over the list you won't catch the error.
The only technological solution I can think of is to tag each item with UPC or chip, but that's fallible at the data entry point and more expensive than replacing a few tins of tobacco every month.