SundanceUK

The pins that hold the wear plates in can be a pain, a small impact gun with a hex bit in usually shifts them, I have also had success with a large pair of wire cutters with one cutting face on the outer edge and one in the hex hole. Another way to shift them is a good old hammer and small chisel to tap the outer of the bolt flange around and break the hold of the corroded pin.

I used to replace these bolts with stainless equivalents, but they are a little soft when trying to undo again nest time the caliper is stripped down, so now I fit Titanium ones. Very strong and will not corrode. New wear plates can be bought online if they cannot be straightened good enough.
Note, also re-tap the holes in the calipers, it helps. I also fit new bolts that bolt the two halves together. Top of me head I think they are M10 X 65 mm.

Sundance