First, you MUST provide a receipt from a shop to make a claim. I am not a shop but I got my IMACS (Auto AC) license in 1992, and replaced/repaired numerous AC components but it’s not good enough - rock wants you to pay somebody to be legitimate. Second, you pay shipping of the defective part AND replacement part if you are lucky to successfully jump through other hoops. And finally, they only replace a defective part with the same manufacturer.
Why not buy directly from Denso (https://www.densoautoparts.com/) ? It’s OEM and A LOT cheaper than stealer.
As I rule I just don’t return stuff. I did get a bad oem water pump from rock but for $25 just threw it away. They also sent a wire set for an 8 instead of a 6 but could still use it. Other than that no issues over the years. Stuff does come from different suppliers and warehouses though so that can be more risky.
Buy six, get two more free!