Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Very disappointing

When I received the Littermate it did not work. I called Littermate customer service. Tech support tried to reconcile the problem, but could not. So, they did replace it, for $10 more and I had to send them a bunch of proof of purchase stuff. At any rate, they did send me a new one, but it is very finicky, it sometimes works, even with premium clumping litter, it works sporadically, For such a costly product, it is disappointing.