Bests & Worsts Reviews from Amazon

I own a photographic agency and we own six Nikon D800 cameras. We also own 24 Nikon OEM EN-EL15 batteries. I bought two of these batteries from Amazon via a store called "Kellards" for in car use at the Daytona 24 Hour race. The batteries came in OEM appearing packaging. Both batteries have failed in less than a month of use. 24 batteries and only these two batteries (we date and mark every battery purchase with labels on the bottoms of each battery) stopped working in less than a month and after TWO charges cycles! TWO. Both will not take a charge and completely have stopped working. Dead. Zero power. As, noted, we have 22 other OEM Nikon EN-EL-15's that have never had an issue in 12-20 months, with 50-120 charges each, I am heavily inclined to believe these are counterfeit. No proof, but we've been shooting with Nikon for a decade plus and have owned over 150 camera batteries and 600+ Nikon OEM batteries and have never had a problem. Having one fail, ok, rare but possible. Having ONLY these two batteries fail, both from the same supplier, has be firmly believing something isn't right with these specific batteries. Now, to make thing worse, I went to return these today, and surprise, I am 3 days outside my return window. Not happy with Kellards or Amazon, and I will be writing Amazon customer service immediately.