I have a message saying 'Service, check gearbox, ABS' and when I start driving or come to a halt, the automatic handbrake comes on (I presume that is what the 'P' in a triangle sign means) and it does not go off until I reach about 20 mph. Any idea what this could be and how much it would cost to fix? Sooooooo fed up as have had one fault after another with this 54 reg car. Would appreciate any advice.