The use of car-jamming devices to steal from vehicles remained a headache, Gauteng police commissioner Mzwandile Petros said on Tuesday, November 6, 2012.Petros said: "This crime has been on the increase across shopping centres in the province. It is creating problems in Gauteng."Petros presented an overview of the 2011/2012 crime statistics to the Gauteng community safety committee in Johannesburg.UNAWARE OWNERSThieves use household remotes to block car remotes from locking vehicles, with the owner unaware that the car is unlocked. They are then able to help themselves to valuables in the vehicle as soon as the owner walks away."These criminals know that when you park at a gym, you leave valuables behind in the car, and that is when they wait nearby, ready to strike."Though police were working closely with security guards to fight the crime, motorists also had to be alert and make sure that their vehicles were locked before stepping away.