right from what im reading is......... your so called BROKEN key opens the doors(central locking)and STARTS the car is this correct?engine stays on????? if so then the immobilizer chip is working correctly :) this is the bit(chip)that costs a arm and leg at the dealers. so im thinking all you need to do is reprogram the remote to the car,this you can do yourself,read your manual or look in the faqs for reprogramming remote keys,this may take you numerous times before you get it, but the good news is it sounds as if you will not have to part with vast amounts of dosh. ;)