Bests & Worsts Reviews from Amazon

I bought 4 of these altogether, and found them very useful for measuring electrical loads. However, 2 of them have failed -- the LCD display goes blank. Fortunately, the device is passive, so that attached appliances continue to run, but the information is lost. One of my failed P4400s was returned to Amazon for credit, but another one failed after Amazon's 30-day limit on returns. I wrote P3 International, but they never responded. Although I love the device, any manufacturer who doesn't respond to a customer inquiry like this gets an automatic 0 stars (1 in Amazon's system). Update -- all 4 have now failed with the same symptoms.