Sigma Invalid charge to my credit card Cincinnati Ohio

I found a charge for $9.70 pending on my credit card and knew I did not make it. When it was posted I found out it was from Sigma and the only information that I couold find out about them was the phone nuimber hey listed with the charge. When you call the number you get an answer machine that doesn't identitfy the company name and asks you to leave your name and number and they don't call you back. There is another complaint posted with the BBB about this company for the same thing and the BBB could not get a physical address for the company or any response to their phone calls.

Greatbear100
Johnston, Rhode Island
U.S.A.