Help W/Aftermarket Alarm System and False Alarms

I got a predator 3900am off a friend, it's a 2 way pager alarm. He has never had a problem with range or false alarms. Was in his 96 golf td, now in my 93 golf td.

After i installed it, i could not get the siren to sound at all, and the range has always been crap, we're talking i have to be 3 feet from the antenna (mounted on the windshield, not behind tint)

So i got the alarm brain and remote replaced under warrantee.

Still got bad range (new battery in remote) and the alarm will sound the warning chirp and page the remote usually about 2-3 times a day. The shock sensor is on the lowest setting, and i never hear a peep from the stock alarm. Iv'e witnessed it going off when i was within 20 feet of the car, so i know nothing has bumped into it.

This is driving me mad, and i'm almost ready to get a different alarm, but i'd rather not do all the wiring again, any help?

my thoughts.....

As far as range goes, make sure the antenna wire isnt bunched up anywhere, make sure its spread out all the way....I found that to be helpful. As far as the shock sensor...theres an installation problem somewhere. I dont have any knowledge of that alarm, so I cant help on that one.