World Book, Inc. Bait and Switch-I order two books for $1.98 and they sent $100 book set Internet

 On 12/25/17, I ordered two World Book "Bolt!" Books for $1.98. They proceeded to send me their "Welcome to Reading" book set, which costs $100.00. When I contacted them and made them aware of their error. I requested a postage paid return label from them, and they told me to send them back at MY expense. I contacted my credit card company to block them from further charges. According to the letter that came with the books, they were going to be billing to my credit card $10 per month installments payments for 12 months. They keep sending me harassing emails, as if I was the one at fault. They sent me the wrong books, and I don't want them. I've told them that the books are still wrapped in plastic, and they can have them back.