If it's a VW, pick up a Ross-Tech VAG-COM + VCDS, locate your Telematics unit (OCU, online communications unit) and remove it; mine was behind the instrument cluster. Then use VCDS on a laptop plugged into your car with VAG-COM, and code out the OCU from every module giving fault codes for its absence. You will probably lose the microphone, as in my Mk7 the microphone line goes through the OCU. Finally, optionally, you can code out your infotainment module's bluetooth features thus taking away another avenue for passive surveillance.