Post '94 there were two patterns of migration - skilled people left the country (e.g. to Usa, Canada, aus and new zealand), and unskilled people immigrated to South africa (mostly from other African countries). The size of the illegal immigrant population is difficult to estimate, but probably 10% of the population.
What was the result of this 'free' immigration?
Higher unemployment for the poorest of South Africans, increase in crime (with a large part of crime done by unemployed illegal immigrants) and then of course the fairly recent xenophobic killings(which saw a return of the brutal necklacing killings). I think it would be justified to say that illegal immigration is the biggest threat to stability in SA today.
TL;DR: South Africa should be used as an example of why immigration control is absolutely necessary. illegal immigration threatens the poorest of the poor (those struggling to find employment), leads to higher crime and threatens societal stability.
Ps: typed on iPhone, please forgive typos.
What is