When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Have an upholstery shop fix it. That will cost a LOT less than a new part, which isn't available anyway. You'd have to scour the breakers' inventory and hope to find one. I'd think it'd be best to do both sides if the color isn't spot-on the rest of the interior.
I tried several upholstery shops, no joy. Most were up front and said they couldn't match the color, the one that said he could, couldn't. I finally found a useable panel at Pacific Motors (breaker)
Have seen them pop up on eBay occasionally, but few and far between (sold by breakers, as Cee Jay said). Get the part number (don’t have the parts catalog handy) and try googling for it, you might get lucky. Just make sure to check any pictures carefully, no need to buy one in worse shape than your own.
If it isn't torn / missing pieces, can't see why any upholstery shop couldn't glue the original material back down (thinking the endless posts about dash leather shrinkage...).
@restd The damage is not unusual for Florida and Texas cars.
Part numbers are different for coupe and convertible. Part number may not help your search.
Use the OEM nomenclature: Interior quarter trim panel (rear lower).
Used panels should come with working sliding cover/doors or be discounted, dollars off.
If doors are missing: suspect damaged track. More discount if you want to disassemble and reuse your track.
Unless you are lucky enough to find a pristine replacement:
1. remove your quarter panels for inspection, and if good, repair.
2. locate black leather or leatherette suitable for repair.
Imitation is easy to find. The real thing may be salvaged from damaged XK, XF or other parts.
3. Carry the panels and material to a shop or do it yourself.