So will they fund failed courses? The answer is yes they will.
If you have failed a course, you can read this article if you want to find out about NSFAS funding you if you fail. You can also read about the N+ 2rule in that article.
According to the NSFAS policy agreement, students must pass at least 50% of their modules as well as meet the academic requirements of their institution in order to continue receiving financial aid during the course of their study period.
You can visit the NSFAS website for more information.