Siyazama Group don't pay Consultants for work completed and signed off

I was contracted by Siyazama Group to assist them with assessing their current contact centre which handles B-BBEE Skills Development. I finished the work in April, and have still not been paid. While it is not a huge amount owing, I am an independent Consultant and rely on honest, paying clients. Not the case with Siyazama even though they state that: Responsibility To be accountable to our promises