You should contact your bank/CC company & report this. They might be able to cancel the transaction... most will have a department to deal with scams/fraud.

Did you get a receipt when you paid? Or an automated reply? Have a look & see of there's a phone number or email address on that.

I'm not sure if there's anything about 360Share in this thread. Even so, you might find something useful
http://www.gnutellaforums.com/showth...threadid=44499

Good luck!