You should be as careful with your online security as you are with your security at home. If you are the victim of an online crime, you should report it to the SAPS at a police station. A cybercrime, such as online fraud, is still a crime, and must be reported in the same way as any crime that may need to be investigated:
ISPA has published a more detailed advisory on this topic.
If you don’t want to report a crime, but wish to report possible online fraud, or suspicious activity, you can log a query with the national Cybersecurity Hub.
If you want to report a problem web site that is hosted by an ISPA member, you might be considering a take-down notice.