Mine just gets worse , Mitsubishi dealer here in Kent says its a design fault, either the shims aren't thick enough or the pads are too small , either way there's too much movement as the pad touches the disc , hence the " click/ clunk" noise. Only remedy seems to be to keep re-greasing the pads & shims with copper ease as this masks the click , only a temporary solution though as it keeps coming back .
Just ordered a whole new set of pads & shims , this will be the 3rd set . The noise is really annoying and often embarrassing if parking as it can be quite loud.
Hopefully 3rd time lucky as mitsubishi won't/ can't do anything to help