Try this site: Car-Part.com--Used Auto Parts Market
When I looked for 2015 MKC parts, a salvage yard in Wisconsin came up indicating they have at least some parts for an MKC. I don't know the exact name of the part, so I couldn't do an exact search.
There's bound to be totaled MKC somewhere in the US or Canada, from which you can hopefully get the part.
If you check the parts catalogue (Quarter Trim Interior Panel) there are may variations on either side - like trim level, color and options like THX, or 10 speaker or no sub (if its the side with the sub) plus there were running changes (may date ranges) so you may have to add build date to the mix. FYI - I have a MKX loaner today - same issue could happen with that vehicle also.