Unaaceptable delays in paying supplier invoices

I did some work for a Professor from Harvard, who is working with the University of Johannesburg (UJ), and invoiced everything during August '22, and, despite "jumping through all the hoops" I was asked to, including completing certain forms twice, I am still waiting to be paid.

I can only warn anyone wanting to supply anything to UJ, including services, to insist on upfront payment, though that will probably also never happen, so you will end up not doing the work. I will DEFINITELY never do any work for anyone associated with UJ, where UJ is required to pay me after this experience.