Bests & Worsts Reviews from Amazon

Earlier this year, we ordered the Safety Siren Pro Series3 for $130, for a house we recently moved into. After a couple months, we decided that we were uncomfortable with the readings in our kitchen, given that we have a 5-year-old daughter. So I contacted a few radon mitigators. One asked what device I was basing my concern on. He warned that the Safety Siren Pro Series3 is, in his experience, notoriously unreliable. He pointed out that some of the relative readings I was seeing in different parts of the house didn't make sense. He suggested that I purchase a AirThings Corentium radon detector. I did (for $200), and got much better news. I contacted FSPI, the manufacturer of the Safety Siren, to ask them what might be going on. I was told to side-by-side test with the Corentium for a couple more weeks, making a few seemingly-pointless modifications to my testing set-up. (Interestingly, they never suggested that the Corentium might be the problematic unit.) We got the same results (see the attached photo, taken at that time). FSPI told me to send the unit in, with no offer to cover the shipping. I asked that they just keep the damn thing, and cover the $130 I had paid for it. It had taken me well past the return/refund window to figure out that I had probably purchased a defective item. (It would have cost me $1000 more, in radon mitigation, had I not encountered an honest mitigator who knew the mistake I had made in purchasing a Safety Siren.) Of course, FSPI refused my request for reimbursement. I received the unit back earlier this week. They have 'adjusted the calibration factor.' For the moment, its readings match very closely with those of the Corentium. So we are stuck with a detector that is, at best, redundant. I was thinking I could lend it out to friends, but given its dubious reliability, I'm not sure anyone will even want to borrow it.