Hi T2D!
Your situation is unpleasant, I know, and I'm sorry about it. But I wouldn't worry too much about it. I'm sure people who like your work will be patient and will either use alternative payment methods right now or will wait until later to order using MasterCard.
I know from personal experience how frustrating it can be to have technical problems that result in the loss of sales. In my case, it's mainly been the lack of good models, leading to a lack of regular releases and thus the loss of potential sales. Heck, it took me 5 months to release a second video after I released my first one because I couldn't find the right candidates, and that really hurt. After all, without new releases I can't make money to finance the production of more videos. Even today I find recruitment to be very challenging (though not through lack of trying). So I have a good idea how you must feel right now.
However, since your work is of such high quality (as far as I can tell from reviews and the cool samples I've seen), rightly earning you the support of lots of people from the TMF, people who can't use the currently available payment options or prefer not to use them are likely to get in touch with you later, once you figure out a new system to get around your MasterCard problem. They won't let you down. So while it's possible that you're losing a few sales right now (then again, maybe not), I hope and believe that you'll make up for it later. Believe me, this temporary problem doesn't make you any less of a great producer. Hang in there and don't despair.
By the way, I think that taking the time to inform people of the situation is a very good move on your part. One has to admire a vendor who honestly admits a technical problem and works hard to offer customers the best service possible. However, there's really no need to apologize. It's not your fault, and you're doing your best to fix the problem. I think you're being very professional about the whole thing. A good example to follow.
