knipatt.com Fraudulently charged my debit card without my authorization, Internet

Today I noticed a pending charge in the amount of $4. My online banking statement listed it only with the date and the amount, which I thought was very strange. It did not list the business that the charge was going to, so I was left with no way to contact anyone. I called Bank of America customer service and they provided me with a number for the "business" charging my card, 813-358-4642. I called but, shocking I know...no one was available. The recording I reached is that of a woman, with an accent, stating "You called Knipatt.com, unfortunately all the support service operators are busy at this moment. Please address your appeals to knipatt.com" In other words, I've been scammed out of my $4. I have read reports that people think this has something to do with making AT&T payments, well I have no dealings with AT&T. So many have been effected by this scammer, they have to be stopped. Don't just brush this fraudulent charge off, I feel like they are testing to waters for bigger transactions. The scariest part about this is, I only had $4 left in my checking as I often carry cash. What if there was more? How much would they have taken?