Rear Brakepad fitment issues

[mrderv]

Has anyone had issues with pad fitment on the rear discs? I replaced the discs and pads 2 weeks ago (pagid discs and eicher pads). However, the rear pads make a knocking noise when braking. I stripped it all down and found the pads are loose in the carrier (about 1mm movement), allowing them to rattle by hand.

I bought some Pagid pads today thinking the Eicher were budget poo, went to fit them, and they have the same issue.
I've refitted the Eicher ones with some makeshift shims for now.

Can anyone recommend some proper fitting pads?