[mattwinslow]

If you want to ding the seller further, leave a negative feedback response (for the seller) on that order.

Mark the reason as "item not as described" and don't add any additional text that would allow the seller to claim the feedback was "product related / a product review".

Speaking from experience as an FBA seller for the past seven years, those are nearly impossible to dispute with Amazon's seller support staff...even when the buyer is incorrect (ie they contact you via the messaging system and admit to buying the wrong product or misreading the product description). Enough negative feedback ratings and the seller's account can go under review and/or be closed.

[kalleboo]

But if the item was commingled, then it wasn't that FBA seller's fault and you're punishing someone who's innocent...

[dawnerd]

Guess the lesson here is, if you're a FBA seller and you don't want that risk, opt out of comingling.

[mattwinslow]

If you wanted to be sure it was warranted, take a look at the seller's feedback prior to leaving yours. If there's a hint of buyers with similar issues - fire away with a clear conscience.

If you've opened a dialogue with the seller via the messaging system, you should attach a picture of the item with its packaging. IF the seller is innocent (and consistent in their processes re: labeling), they might be able to open a case with Amazon along the lines of "this was commingled inventory - we always apply our label vertically over the item's barcode and our customer received an item packaged with the barcode applied horizontally...therefore you sent the customer another seller's inventory."

That would be a semi-tenuous case to make, but would have a flying chance of working, particularly if the seller had an inbound shipment for the same SKU that was due to arrive at an Amazon warehouse and had left prior to the customer's issue surfacing.

In general though, if there's a shred of doubt...don't worry about the innocent seller. The seller (hopefully) has enough sales volume that your feedback will be lost in the crowd. If not, well, maybe they aren't a good fit for Amazon and you're doing everyone a favor.

[aninhumer]

The seller is responsible for delivering the product you paid for.

If they use a fulfilment service which cannot reliably achieve that, it's their problem, just as it would be if they used an unreliable courier.