As expected, three days later, and I have not yet received my callback from Charles, which was supposed to occur "24 to 48 hours" later. I have filed a complaint with the Better Business Bureau via e-mail, and I'll keep you posted on that.
To give credit where credit is due, I received excellent customer service this week from Kidde and Brink's. On the same night, I discovered my Kidde smoke/carbon monoxide alarm and my Brink's outdoor motion detector were not working properly. I called each company's toll-free line yesterday afternoon. The Kidde operator was extremely polite and promised to send a free replacement immediately. She said it should arrive in 7-10 days and gave me some instructions (not in the manual, I believe) on what I should do with it before installing it.
At Brink's, the service agent was not at his desk when I called, but I left a voicemail message with my name, number and description of the problem. He was also very polite, and, after some discussion, decided that my sensor was defective. He also promised to send a free replacement sensor immediately. No hassles or arguments, and certainly no discussion over whether my products actually worked properly. This is how customer service is supposed to be.