Placed an online order from a third-party seller on Walmart.com for a set of Pistons. The ad stated quantity of 8. The ad listed the price of $296.99 then had a reduced price I placed an order the seller accepted billed and shipped. After shipping the seller informed me that the ad had a misprint in the description the quantity was wrong in the price was wrong but charged me the and sent me one instead of the set of 8. When I contacted the seller he told me that he was aware of the ad discrepancies with the quantity and price and told me it was my fault that I should have known better. What can I do.