I have a Vauxhall Meriva 1.4 (09-plate). A continuous squeaking comes from the wheels but stops when I depress the brake pedal and also when I turn the steering wheel left or right. It starts again when I straighten up. It can also start any time and stop anytime for no apparent reason. This happened previously and the mechanic thought it was the heat shield on the brakes. I didn't know brakes had heat shields.