Cybernet Ventures Adultcheck Fraudulent charges to my credit card Internet

I have discovered that charges of 24.95 have been made to my credit card in each of the last 4 months, starting in February, by Cybernet ventures. When I called their toll-free number they insisted that I must have signed up with Adultcheck and just don't remember. I don't believe that it is a coincidence that the first charge was made on the same day that I made a charge of $7.00 elsewhere online. I have twice e-mailed Cybernet asking for my password (which I know doesn't exist) and neither e-mail has been answered, even tho they claim that they have record of having sent a reply but they cannot tell me what that reply was. I have requested a full refund but was told that they had to turn it over to their Credit Dept for investigation. I am still waiting for a reply from them.

Sam
Los Angeles, California
U.S.A.