The only way that hole can wear is if the lower link bolt is not tightened properly and it is actually loose allowing movement. I've never seen one worn there myself.
^^^ Ditto
From the description of wear, loose at either end and tighter in the centre, that sounds very much like a loose bolt. It should never move or rotate, it's a rock solid connection when torqued properly. I'm slightly surprised you can't get it to work even with the wear as described, I would have thought the crush tubes in the damper & link plus two washers either side of the carrier would tighten up into a solid connection. There must be a lot of wear if it still moves after tightening up and that sounds like an insert is required. Or, if it's not worn centrally, a J prep with some weld at either side and ream the hole back to size ?