My one did this same wheel, by the time I got to a garage it had killed the disk as well as the pads.
We were up in the Lake District on holiday, so couldnt have a look myself.
In the end it was down to the sliders being corroded, guy said he had to use his big hammer to free them off. But had scored the disk so had to have 2 x disks and pads.
Got new sliders and made sure it was all freed off when I got back home.
Has needed looking at again though, they do have a weak spot. New caliper next time, for me.
