Car Alarms: car alarm defeated, 2006 chevy tahoe, chevy tahoe

Question
In the last three months my daughters been using her brothers 2006 Chevy Tahoe while he's overseas.  He had the big fancy rims on and they came into her driveway, got into the car for the key to the wheels with out setting off the alarm. Heck, they got them all, and left it up on blocks under my Granddaughetrs window.  Yesterday she and my Granddaughter were in a park near by their house, only to return to the car and find two guys in the car, who fled in the own vehicle when they noticed her. She said she had the alarm set both time, and I'm sure she did.  How are they defeating the system (it has a remote start), it came with this alarm from the dealership,not after market.  We're all more than a little conserned and want to know what can be done.  Thanks for your time. George

Answer
Really not enough to go by here to assume anything George.
But it sounds as if the OEM system is not working.
I'd have GM do a diagnostic to find out why.

Too many variables I am unclear of here.
Best thing is to start at the manufacturer for these
answers, then if no joy, you will want to look at
other ideas. GM's are very well secured these days.
Can not start it without the proper key, and
if armed, the horn and headlights would start
flashing and blarring. Only way I know of to
get around a new system is have the keys.
So have GM chime in here. See why they're "security"
system failed you.

Let me know what you discover.

ALARMTEK
CARALARMMAN.COM