I can't see how the AA would have changed the tone, I used to work for them and an easy break in was to power up the reversing light cable (unplug the cable from the gearbox switch) then apply power to either of the wires and the negative to the cars chassis. One wire would just light up the reversing lights, the other would power up the whole dash, ignition etc, then you put a plastic wedge in the door and wind down the window as the switch is now powered up. I had various tools made up to do this and I used a fused 12v battery. Really cant see anyway they would have changed your horn tone, the Vag mod is only the alarm siren tone anyway.