May you please assist me.

I was employed as a Public Liaison Officer (Call Center) by a public service organization (Government Department) in South Africa in 2009 on a one year contract, 2010 it was renewed (another one year contract), in 2011 i was given another one year contract, 2012 i was given a three year fixed contract which expired in September the 30th.

My post was advertised last month, giving me a hope that i will become permanent because i have bee working in the very same position for 6 years now on a contract. After applying for the post, the post was frozen with immediate effect for unknown reason.

They made me sign another three month contract which will expire in December 2015. I would like to know if what they are doing to me is legal and of sounding labour rights because now i feel exploited and used for 6 years without getting benefits, 13th Cheque, Medical Aid, Pension fund,  Study Aid Bursary to name few.

I would like to be assisted

Thank you