Why should other students do the teaching -- don't they have their own classes to worry about? Why would your students want to learn from other students, or from a website, instead of from an expert? And isn't teaching what they pay you to do?
But if a student isn't learning, they have choices. That's it. If a student has a problem asking peers for help (who may be better experts than their teachers), doing reading beyond their book (which may offer better or more recent information than available in the text), or finding a way to learn what they need to learn, then they aren't going to be able to function in the real world. Because in the real world, people don't teach you things, you must seek knowledge.
I am not being paid to teach anymore, I went off to industry after grad school because I needed to make a living. When I taught, I was engaged every day, and was the best teacher I could be. That included 6 hours teaching every week, 3 hours of attending the course that I was teaching (I sat through the same course 7 times), with another 4-6 hours of office hours every week, in addition to any other courses, research, and contracting work that I was doing.
In particular, there are people who have taken your class before. The teacher is the primary person who has ostensibly taken that class before, but when that fails, there are students who have taken that class before. Find the few who got As, and ask for help. Or if the book is awful, ask around for a better book. Or hell, MIT's got their OpenCourseWare for more and more topics every year. As students (really, we all are), it has never been easier to learn.