I called the number after seeing an ad on TV for a $10 book with no shipping charge. After the automated call got my credit card number, it went through a long series of "Do you also want to purchase" to which I said no, then had to confirm no, then it went to the next item "Do you also want to purchase" and had to confirm the no for several items.
I figured I could live with the $7.99 shipping charge. In spite of confirming no on all extra items, Who Knew shipped the extra books and charged my card $47.99. I was able to reach a person (in India) who tried to convince me that I should keep the books as Christmas presents, but finally gave me the instructions to return the books at my cost after I got really pissed.
The customer service rep wasn't at all surprised when I said it was a scam and that I was going to file a complaint. He even offered the "Better Business Bureau"
Monetary Loss: $38.