alarm won't stop going off!

[Unlucky Alf]

My alarm has gone off five times so far since 8am. Noone has gone near the car, drove past, or touched it. All windows are closed and the motion sensors haven't been moved. It's not done it through the night, just this morning. It also did it a few times the other day. It used to do this before but just stopped :s
it's really annoying me. I've just gone out and started the engine up, and messed with motion sensors and it hasn't done it for about 10 minutes. But is there a way I can adjust the alarm sensitivity or anything?
On Saturday night I pressed my lighter down and blew my head unit. Since changing that it now flicks over to traffic radio all the time too.
Sorry if this has been asked. I'm on my phone so it's harder to search.

Edit. Spoke too soon. It's off again!!

 

[Clart]

Cover the motion sensors up with some tape, or turn ignition on off, on off again. Lock the car quickly and it will disable the sensors.