SAIF zone employment law

Good day,
I was recently retrenched by a company in SAIF
My last salary check was held ransom until I agreed to accept it as final payment. I was broke, this was blackmail and I did state that to them at the time.
Before that I asked MOHRE for help but they said SAIF was outside of their control.
I wrote to SAIF but no response.
My contract stated clearly 30 days notice and I was given a good reference so the parting was simply for company restructuring, I was retrenched not dismissed, I received no 30 day notice. I had worked there for over 12 months and received no end of service benifit.
Is this all legal?