I have the alarm fitted to my dci.
Worst think I ever bought it cost me £300 and is no end of trouble although its ok now after going back to the dealer loads of times.
The main problem with the alarm is the sensors there ultra sensative. I had mine turned down in sensitivity by the dealers which help fix it more or so even though they could do with being turned down a little more.
Another sensor problem is the sensors are sometimes so sensitive that the airvents on ther own can set them of. The air coming into the car though the vents is sometimes enough to set them of. Try closing the vents till you can get the car back to the dealer.
Also make sure the bonnet boot and doors are closed as this sets the alarm off after a few seconds.
Be carful if you do decide to lock the car manually, cars have been known to be stolen by thieves setting the alarm of time after time, convincing the owners to turn the alarm of as its broken and then the thieves can break into the car with no trouble.
EDD