To turn Bluetooth on/off, go to menu, then SYNC settings and move to the right. There you can tick/untick Bluetooth.However, your garage may well be correct. Your battery would be nowhere fully charged evenbefore you stopped using the car for two weeks in the cold weather. Therefore, I'm not surprised that you've got a flat battery. Just get it charged and try to use the car a bit more in the winter, not just a short journey.
I hope this helps and good luck.
B-Max Titanium 1.0 125bhp manual City Pack.