Recently, I sold my lightly used motherboard to a buyer through ebay. A few days later, I shipped the item out and began waiting for payment. About two weeks later, yes two weeks, I asked the buyer to pay through an invoice on Ebay. (At this point the box has been delivered according to the tracking number). Only to have him tell us that he had not received the invoice. I replied saying ok and that would re-send the invoice. Upon resending the invoice, the buyer than says that he had never received the item. At this point I decided to call Fed Ex and UPS. Upon calling UPS, I learned that the item had been not only delivered to the destination but had been handed to a man in the house. When I told the buyer that this had happened he said that he had actually found the item and that he would pay us, however he never did. We allowed him a day to complete the payment so we did not come off as rude. The next day he contacted us again saying that he had found a different motherboard and that he would continue refusing payment. What can I do to fix the problem that I have caused by not waiting for payment before shipping?