I had to revoke my wildcard cert a few weeks ago. You can tell them why you did that. As far I know they decide to charge you on a case by case basis. When I revoked my cert I got an email 3 minutes later saying: "Revoked free of charge".
"Class 1 certificates aren't revoked free because we receive too many requests
daily (specially for the Class 1 free certs) and would we have revoked them
all, our certificate revocation list (CRL) would have been blown out of every
proportion."
In a further back-and-forth, the admin proceeded to tell me how much bandwidth I would cause them (I don't even care about being added to a CRL for a personal domain).
Edit: Sorry, you did say a wildcard cert, which sounds like a paid cert, so would offer more "service" I'm guessing.
