An unauthorized seller had to get your product from somewhere, and the somewhere is almost always upstream. A distributor's overstock. A closeout you were glad to move. A retailer who ordered too much and sold the excess on. A pallet of short-dated stock dumped on a liquidator, which is next month's cheapest offer on your own listing. Most of the enforcement work is upstream, and the brand that spends its time reporting the seller on the listing while ignoring the distributor who supplied them is bailing water with the tap running. The first question is not who is selling it. It is who sold it to them, and the answer is usually in the brand's own shipping records.
The fix starts in the agreements, not on the marketplace. Put resale terms in the distributor and retailer agreements: no marketplace sales without written authorization, and no selling on to other resellers. Those terms are the only leverage the brand has over genuine product, because Amazon does not remove a seller just because the brand has not authorized them. If the product is genuine and new, the seller is usually allowed to resell it, so reporting genuine resellers as counterfeit does not work and can put Brand Registry access at risk. The agreements are the enforcement. The marketplace reports are for counterfeit, trademark, and listing abuse, and only where the evidence supports the report.
The tool that finds the leak is the test buy, and the test buy works because of the lot number. Buy the product, check the lot number, expiry date, seal, and packaging against the brand's records, and with lot-level shipping records the lot number points to the distributor or retailer the unit passed through. If the product is serialized, the brand can track the sale back to the original purchaser and take remedial measures. That is the whole method, and it is why lot-level records matter: without them, the test buy proves the product is genuine and nothing else, and the leak stays open. With them, the test buy names a name, and the name is the start of the enforcement.
The test buy also decides what the report can say. If the product is counterfeit, the evidence supports a Brand Registry counterfeit report, with the test-buy photos, lot codes, and packaging differences attached. If the product is genuine but diverted, the report is not the tool, and the tool is the distribution cleanup: the reseller agreement, the MAP policy, and the allocation rules, enforced with legal counsel. Every report filed should be backed by evidence, and every report filed without evidence goes on the brand's record. Repeated rejected reports hurt standing, so the discipline is to test-buy first and report only what the evidence supports.
Three moves, in order. First, stop dumping short-dated stock on liquidators, because that pallet is next month's cheapest offer, and the saving on the warehouse is smaller than the cost on the listing. Second, tighten the agreements: no marketplace sales without written authorization, no selling on to other resellers, and allocation rules that match real demand instead of rewarding over-ordering. Third, enroll in Amazon Brand Registry, which is free and needs a registered or pending trademark, and gives the brand one place to report suspected IP infringement and store policy violations. None of these is a quick fix, and none of them removes the seller who is already there. What they do is close the tap, so the next pallet does not become the next leak, and the listing price recovers because the supply stops growing.
If this topic is useful, these earlier guides go deeper on connected questions: Walmart Brand Portal: The Claim Form Is the Whole Game, Gray Market Listings: When Authorized Stock Leaks, and Project Zero: Amazon Hands You the Remove Button, Then Grades Every Press.
Usually upstream: a distributor's overstock, a closeout, or a retailer who ordered too much and sold the excess on. Most enforcement work is upstream, in the distribution chain, not on the listing.
Buy the product and check the lot number, expiry date, seal, and packaging against your records. With lot-level shipping records, the lot number points to the distributor or retailer the unit passed through.
Not just for being unauthorized. If the product is genuine and new, the seller is usually allowed to resell it. Amazon acts on counterfeit, trademark, and listing abuse, with evidence, not on unauthorized status alone.
Stop dumping short-dated stock on liquidators, tighten reseller agreements against unauthorized marketplace sales and onward selling, and enroll in Brand Registry, which needs a registered or pending trademark.