Just keep selling ticket until you run out of paper.
I had to look up the word "refund" in my English-Spanish dictionary this morning, but I´m not optimistic. "Hi, we´re here for the soccer game." "Stadium is sold out" "No, I don´t think you understand. We have tickets already." "Stadium full" "No, really, we have SEATS - GOOD SEATS" "Stadium is full. No more enter" That´s all I feel like writing right now.