I think somewhere in the fine print (at least on 
the US site) it states that they will continue to 
use your card by default after you enter it. 
However, if you write to them and tell them they 
are not authorized to charge anything more to it, 
then tell your credit card company the same thing 
(and provide them with a copy of the letter you 
sent to Ebay), you should be able to prevent 
future charges. I can't imagine any clause they 
could put in that would override you specifically 
telling them you will not accept further chrages, 
provided you are willing to pay for their
"services" (*smirk*) by another method. . .

Many Sharp Smiles,
--Drac  (stuck in Ohio. . .)