One of my dads vans alarm keeps on going off for no reason over night, our mechanic took it down to his place yesterday afternoon I think and disconnected the battery. ( alarm didnt go off during the day) then today he rang up my dad saying it kept on going off over night again even with the battery disconnected? Whats going on with it, hes got someone from vw going to look at it. I think its a 57 plate.