Hi, I've just bought an '07 A3 2.0 tdi and it has parking sensors in the rear bumper. However when I put it in reverse they don't work. I've looked in the owners manual and it says there should be an option in the menu system to adjust the volume of the beeps but the option isn't there. Has someone just fitted parking sensor dummies or is there a way to turn them on/off? Thanks in advance.