Amazon doesn't sell the kit directly, but even if they did, they automatically list the cheapest seller, even if it's not them. Usually, it's Amato.

None of the companies have a 100% service history, but if a company doesn't respond to problems, Amazon will delist them. I think there's a good chance if you send a photo to Swimming Pool Warehouse, they may simply send you a new bottle of powder. It's worth a try.