Quick answer - there aren't any. Its a monocoque shell and BMW/Land Rover only provided complete side body replacement panels which includes the outer sill cover.
The only after market repair panels are for the inner sill (
https://www.ebay.co.uk/itm/263795604...cAAOSwteJhLIte) and the rear wheel arch panels. Your mates only real options are to find one in a scrappy with decent sills (good luck and happy hunting!!) and cut out the required area to fabricate a repair or find a good body shop who will fabricate and do the metalwork.