The bloke that had his Merc nicked obviously had not read the manual !
"Similarly, Harry Goaman, 25, from Clapham South, came home last month to find his £21,000 second- hand Mercedes C-Class Coupé had been taken by thieves using the relay trick, even though the car keys were in a cupboard drawer 10ft inside his home."
"In addition, all Mercedes-Benz Keyless Go signals can be switched off by pressing the locking button on the key twice, which de-activates the signal: they can be reactivated by pressing any button on the key."