You already said you contacted ebay on the 
issue.  I don't know if they have a phone number 
you can contact if they just are ignoring your 
complaint.  Me personally, i wouldn't ever want a 
copy of someone elses cel.  Were is the joy an 
unoriginal image.  Its like buying an expensive 
photo copy.  

I hate the sellers who say in the auction title -
 "beatiful Ryoko cel, or Perfect cel of Iria" 
then when you go to see the cel the person either 
states, Fan cel, why didn't you say that before, 
or doesn't say anything about it being a fan cel.


More directly in your question, keep buggin the 
hell out of ebay.  Flood their system.  Write out 
your complaint and copy it and keep pasting it to 
emails.  Sooner or later they would have to 
respond.  Ebay doesn't want to break any laws so 
if they think that you have a good argument for 
the existence of the auction they will take it 
down, if they think you don't, then it will be 
one of that you can dislike all you want such 
as 'the studio should release more cel's so that 
they are not so expensive' you might just have to 
swallow hard and take it.  

i could just be giving bad advice though.

I would hate someone to make a copy of one of my 
original images, so i hope that you win in your 
complaint good luck.