Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Feliway Zone Diffuser

I bought a refill for the Feliway diffuser.($30.99) I left the house for a couple hours and it smelled like an electrical fire. The smoke alarm was going. I finally unplugged all appliances and the smell was coming from the diffuser. I called the company. They said this was not uncommon. They said I could mail the diffuser to them, at my expense and they would send me a refund or a new diffuser. I really afraid of a product that has such a problem. I will return my refill to Petco. I also bought a NutraVet diffuser($32.99) and it does not emmit such odors.I do believe the products do work, but don't want my house to burn down.