If I receive another from the same vendor, I go to Amazon and give them a one-star review. If you do this too (and I hope you do) then do NOT mention the spam as a reason for the bad review. If you do that, Amazon will remove the review, since reviews must be about the product and not the company selling it. So just make something up instead.
You blockhead. They do that because, I assume, you are reviewing THE PRODUCT through a PRODUCT REVIEW. Your review will appear under THE PRODUCT listing on Amazon, which is used by both Amazon, that Marketplace vendor, and all the other Marketplace vendors.
You honestly haven't figured this out yet? Despite the fact that when you search for the product it displays an Amazon purchase link (usually) and things like "24 new from $XXX.XX" and "5 used from $XX.XX"?
You want to go to your order history, click on the order, and magically there will appear a button labeled "Seller Feedback." Seller feedback is expressly supposed to be about the company selling it, so I'm not going to buy any cover-your-*ss follow-up that claims that you were referring to that button.
Hint: there's also a "Package feedback" button that you can use to complain about Amazon's packaging for the Amazon warehouse-fulfilled orders, which might actually provide feedback to the people who packaged the order.
Stop polluting the product reviews with made up issues because you can't be bothered to figure out how to review a vendor properly.