Hi....
I have read on the various AC (Answer Centre) boards that ebay has credit some of its members on making a misstake on one or two listings but never read anything on 8 listings or more.
You need to phone ebay and if they are having a good hair day they might credit 1-2 or even the full 8 listings or maybe none, its worth a try.
Post back on the results.
Good Luck and don't hold your breath too long.:-)