Hello! I work for Billpoint and am sorry to hear about your experience. Technically, it's not prohibited for sellers to charge a Billpoint fee or a convenience fee. But, as tealt noted, it is certainly prohibited by
certain state laws and the policies of the payment systems that we use (Visa, MasterCard and Discover) to surcharge for credit card transactions and not for other types of transactions. From the eBay perspective, the seller must disclose all terms of sale in the item listing or follow-up correspondence.
For Billpoint items, you would have received Billpoint invoice, which you could review prior to payment. My only suggestion would pertain to future purchases -- that is not to pay Billpoint invoices or any other invoices with payment terms not previously disclosed to you by the seller.
