If they advertise JAR approval they must show the approval no. Then check with the CAA against that number. Simple.
PPLs in SA can be converted to JAR by writing the exams, and doing Flight test. If you've got more than 100 hours, then only HP and airlaw need to be written.
JAR ATPL ground school can be started with any PPL, not only JAR, so a SA PPL will get you admission to JAR ATPL school, and hour building later will take you over the 100 hours.