I recently bought a 2003 2.0 DTi, after having it 2 weeks a loud squeeling started at the front left, only after about 20 miles or so. It went when I put the brakes on came back when I took them off.
I concluded this was due to a warped disc, I took it back to the garage who agreed and changed the front discs and pads, another 2 weeks have passed and it's started again, same side and only after about 20 miles. It's quieter than before but slowly but surely getting louder. The garage want to change the discs and pads again, but is there any cause for the same thing to happen.
I'd rather they cure the problem than take away the sympton.