I have had my wheels balanced three times now and I still get a slight vibration at motorway speeds which I can feel through the steering and pedals. I seem to have weights stuck all over my wheels. On one side I have weights in three positions and in one part weights stuck on top of weights. Is this right ? The car is a 2012 a3 black edition with 18" rotors on them. Anyone help with some advice on where to take it in the Manchester Area ?