It looks like (from my recent experience) the defacto-standard in online credit card transaction processing, Authorize.net, has gotten too big for their britches. They used to be the only way to go for web developers like me to connect websites to merchant accounts. Now....their developer support has been outsourced, your request is put in a ticket queue and you're just a number to them.
It's okay, I understand. Companies grow and need to be scalable. But the same personalized service I liked about Authorize.net is now what I like about their competitor. : )