I assume that you have already set to the maximum length the micrometric bolt adjustment in the buckle. regarding the dented piece, in principle, you should be able to move the existing ones by removing the rivets or bolts and repositioning the piece a little more to the outside. Some boots have even got pre drilled holes for doing that. If you drill new holes, you have to be careful that there is sufficient distance between the new hole and the end of the plastic piece to withstand the tension.
In any case, myself also having wide calfs, my experience with Salomon's when I tried them is that not only are they narrow at the calf, but also the shape of the boot tongue and the relatively reduced overlap between the tongue and the sides of the liner result in a most unconfortable fit, even pinching the calf on the sides. I could not even close the buckles in the shop without pain.
I suggest that you visit an expert bootfitter if the boot is really uncomfortable.