I will echo those who had said that buying with a credit card is easier to replace than buying with cash, but it's worth talking with them and seeing what they have to say and what they can do.
I remember a good while back I saw Rent on a very windy evening. I had gotten a standing room ticket and it blew away the moment I got to the corner. After making a bee line to the theatre and being informed that the box office couldn't help me, I waited to speak with the house manager. I told her I was in standing room and she told me to wait till closer to showtime. The box office had informed her that all the standing room spots were sold. So, when it was five to eight, she put two and two together, realizing that, even though all the SRO spots were sold and there was one open, that that was the one I bought, and let me in no problem. Granted it was frustrating and annoying especially not knowing if I was going to get in to see the show that I had paid money for, but it all worked out in the end. To be honest, it's worth a shot.