Izak Jacobus Marais - Isak Jacobus Marais

Please help me. I realize now the greater Swellendam district included both Robertson and Worcester, all the way to Swellendam. I paid a GISA research assistant to look at the birth registry in Swellendam and found nothing for Isak. I was wondering how to research myself, for both Worcester and Robertson, budget restraints. Where or who can I approach? I have tried the Robertson Museum too. No records on NAAIRS / EGGSA. Thanks