These related Help pages may answer your question:

• How do I report shill bidding?
  If you believe that another member is artificially raising the price or desirability of an item by shill bidding, click the link above to report it to eBay. Please be sure to provide the User IDs and the item numbers in question. . . .
• What are the rules for selling on eBay?
  eBay's rules for sellers help ensure that transactions at eBay are safe and hassle-free. For example, sellers may not bid on their own items, refuse to sell an item after purchase, or ask a buyer to buy an item outside eBay. Click the above link to learn more about selling on eBay. . . .
• Does eBay offer buyer protection?
  eBay and PayPal both have Buyer Protection programs. Click the link above to learn more about these programs and the steps you can take to ensure a successful purchase. . . .