Re: Alarm randomly goes off.
First Batteries! I'd feel confident in saying that no one should still have the original battery in their cars now. If you do change it first. Poor performing batteries kill these cars. Don't take it to the dealership unless they have a certified crossfire ( Benz) mechanic. After changing your battery you might then be able to differentiate the symptoms easier. The cricket on crack is solely the alarm siren module. You might have other issues, but as stated if you haven't changed your Battery then you really do not know.
Repairing the alarm module by replacing the batteries inside is fairly easy, but remove it and open it first, before buying the Batteries, because if its been bad a long time the Board may be shot, and then you will just have to buy the alarm /siren anyways, If your not confident cutting open the siren and soldering new batteries inside then just buy the alarm/ siren and replace it. This is easy and the only tricky part is having the right tools including a small puller for the windshield wiper arms.