Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Kat's Heater Meltdown

I have purched three of these heaters (two from Amazon, one from an auto parts store). Two of the three have melted the plastic case resulting in a very hazardous condition. Five Star Mfg. Co. was unresponsive. I strongly caution against this product for use on anything of significant value or in an area containing combustable materials.