I started working In the USA on and H2B visa. i was supposed to go
back to South Africa after 3 months but wanted to stay. The agency
said i need to apply for a tourist visa while current H2B was still
valid i did that and got approved. I am now currently on a F-1 status
studying, I would like to go home and visit but have been told i dont
have multiple entry status and will not be aloud back in the usa for
at lease 3 years if i leave, how do i correct this?

Your'e best bet is to contact the USCIS, either at their website
(www.uscis.gov) or at the National hotline (1-800-375-5283). My guess
is that you will have to apply for a multiple-entry B-1 visa, but they
will be able to tell you exactly what to do.