Car Alarms: KARR Auto Alarm, karr auto alarm, dodge charger

Question
I have a 2006 Dodge Charger with a KARR Auto Alarm that came with the vehicle. After disarming the alarm, I open my door and 5 seconds later, the alarm starts to go off again and I obviously have to disarm it again. I have had several vehicles with alarms that have already been installed and I have never had this problem where I have to disarm it twice. This problem is starting to get annoying especially when I have taken my Charger for oil changes or car washes or other various things. Should I take it to a stereo store so they could fix this problem? I am not too sure of the model of the alarm. Thanks.  

Answer
I have not heard too many good things about that specific brand.  I have no real experience with it, so the information is all from other sources.  I would strongly suggest taking the car to a shop to have it looked at, ideally the shop that installed it originally as it should be under warranty and repairs should be done at no cost.