brake calipers

[Kevin]

but as they start to wear down this movement in the calipers gets much worse
its almost like the caliper is not adjusting to the worn pad

They will be adjusting, if it weren't, then you would have extra travel on the brake pedal.

The reason the caliper appears to move more as the pads wear is due to the caliper slide pins coming out further from the carriers. So it ends up exaggerating the movement.

Whether Vauxhall have a cure or not, I don't know, but Vauxhall ain't the only ones with the problem. Clios and micras are real bad, but no ones seems to bother too much. My own micra has done it forever. No harm is getting caused, so I just have silicon sealer on the parts of the caliper that touch the pads. Noise is gone and never returns.

Yes, maybe it shouldn't do it, but we will never get the perfect car, no such thing I'm afraid.