Ceiling Flush Mounted PIR Occupancy Switch

Good while they're working, but I've had to replace three in the last two years.

Had three of these fitted to new build, plus two of sealed version. Electrician bought via wholesaleer, not Amazon.Within two years all three have failed - in different ways. One permanently on, one always off and the third works sometimes, but then is unresponsive for an hour or so before it triggers again. One of the sealed versions has also failed. Considering the price, this is very poor. The variety of ways they fail suggests very poor quality control. Avoid.