I am looking for ideas on how to prevent my car, Toyota Sienna with factory alarm, from being broken into. Someone has gotten into my car on three separate occassions in the middle of the night. My car alarm did not sound off at any time so I suspect whoever it is might have a device to circumvent the system. Luckily, nothing was taken except for some change. I've contacted the local authorities and was not given too much help. Does anyone have any advice on how to deter or prevent these break ins? Thanks in advice.