Instruct: Classify the given review as either positive or negative.
Query: Good when it worked...

The collar worked fine for about a week, dog quickly learned not to bark. To conserve battery strength the collar was turned off when the dog was not outside. The following week we noticed the dog was barking with the collar on, replaced the battery and collar still didn't work. Called Petsafe and went through system checks and identified the collar as defective. Petsafe Rep said that they would replace it, however, three weeks later we are still waiting to receive the replacement.