Do not buy a MECER inverter!

I bought a Mecer 820W Solar Charge Controller 1Kw 25.6V 1x50Ah Lithium Battery Pure Sine Wave Inverter SOL-I-BB-M1L from FirstShop. It's a really good looking and compact unit - BUT - it was faulty out-of-the-box! This has led to a (very) lengthy returns process as FirstShop deal with their supplier (still unresolved). FirstShop tell me that "..the service centre has a backlog to deal with as there has been an INFLUX of returns of these MECER units".