My first solariboost+ was installed in 2015. In July 2019 it went dead, power good. Marlec supplied me with a reduced cost unit (£149) which was installed the same month, now this one has failed in less than three years. The immersion heater element was new about three years ago and still works perfectly. Marlec are offering me another one for £149. Having done some research, it seems failure is common, often soon after the warranty expires. I'm reluctant to buy another, and am looking at a solic200. Any thoughts?