I am trying to figure out how to set up a tutoring site. There is a company that I have been a customer that has a great site, nulengua.com, where customers buy credits, and with those credits they can reserve time with a tutor of their choice. The tutor's schedule is on the site, and the customer can pick from available times, after which the time is listed as unavailable.

I haven't found any software out there that does this, but maybe it exists? That is why I am asking here, because you guys tend to know the answer to just about everything :-)

Thanks for any of your help! :-D