Mine doesn't have an alarm feature, wouldn't own another alarm system for any amount of money in the world. However, I know when one of those goes haywire, it's unpleasant. I had a GM brand in my 1990 Formula that decided to malfunction the moment I pulled onto a car to see about trading the car for a pickup. The siren wouldn't shut off, I couldn't unlock the car to get in a pop the hood. Had to crawl under the car to cut the siren wire, then disconnect the module power. Needless to say, I moved on to another lot before attempting to make a trade.
The parking lamp circuit on the unit is rated at 10 AMP and they include a fuse to install as a precaution in case the system draws more than 10 amps, if it does, the fuse blows and you know you have an alternate route to take.
Why anyone would have a single problem with the unit, and not return it is a question I couldn't answer, the problems you mention are not tolerable, let alone allowing multiple instances to continue to occur. This is where purchasing from Wal-Mart has it's benefits.