Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Customer Service

The sub is OK, rounds out a basic system, low price for basic performance. However, the one I purchased stopped working after about a month of use. KLH asked me to send the power unit into them for repair. I have not heard one word from them since. Phone calls and e-mails have not been returned. It is like I never existed. So be wary, sometimes buying cheap cost you in the end.