Car Alarms: Carbine - someone else got in my car with their remote, things spring, carbine

Question
I've got two problems...   first I have a carbine alarm installed which came with two remotes... the two way and the normal remote.  

Last night, at about 4am, my neighbour witness someone disarming my alarm and got into my car.  I have the only two remotes so there is no reason that should have happened.

Is there a way to change the code or something?  Why would that happen?

If I took out the wire that attached to the remote antena, would that elminate the possibility of their remote doing that until I get it fixed?

Second.....  when I was at a store a couple weeks back, the pager remote must have had a low battery because it suddenly did the melody/vibrate thing.  I replaced the battery but now the remote doesn't do anything except for update the arm/disarm status when i use the little remote.  Is there something I should have done when i replaced the battery?   

I only got this alarm professionally installed a month ago and it was working fine up until these two huge problems.

Any help would be appreciated.  Thanks!

Answer
Well. a couple of things spring to mind.
The installers have a spare remote and are
coming back to steel your belongings.
Unlikely.

Another is that a local kid has a remote that
happens to work here and is happy to play with
the car. Possible.

My take on this is that the system installed may not
be something you want to keep now.
If someone has access now, reprogramming
the remotes won't do it.

Take it back to the installer, explain your issues
and get his thoughts on this. He should want
to help you solve the troubles you are experiencing.

Let me know what you discover.

ALARMTEK