I sell original oil paintings through my website, with customers paying with PayPal. I have my settings fixed so that once a painting is sold, it’s no longer available for purchase and I get immediate notifications from PayPal. But twice in the last week, I’ve had two sales for the same painting processed. I’ve had to apologize and issue a refund to the second purchaser both times. I haven’t been able to get through to anyone at PayPal to try and fix this. Any ideas?