I am contemplating on doing an MBA with Mancosa but I see it has lot of people are douting its credibility,how do I find out if its really credible and MBA graduates are giving biased advice...

This might be useful https://find-mba.com/board/distance-learning/value-alternatives-to-unaccredited-mbas-58288

What are your goals and expectations?

I can't advise doing an MBA from a school that lacks International accreditation (from AMBA, EQUIS, or AACSB...) Maybe see what else is available?

this might sound stupid but is there a cheap accredited online MBA program ? 

There are some good comments on this thread: https://find-mba.com/board/distance-learning/value-alternatives-to-unaccredited-mbas-58288