Boulderjohn suggested to me in a series of PM that perhaps I was not clear enough and was taking too much for granted. So I'll post my PMs to him in the hope of clarifying what I was trying to say:
I don't know what standard NAUI in SA operates under. The current NAUI Experienced Diver standard requires that one be 15 years of age and have proof of at least 25 open water scuba dives to enroll in an Experienced Scuba Diver course. Candidates are first encouraged to take the "next class up," but they may take a written exam and do 4 dives. Earlier standards were somewhat vaguer, as I recall, and just required that all of the learning objectives of the entry level course be met (which could happen in a single dive). These earlier standards (or similar) could still be in effect in SA.
Under previous standards it was possible (though rather unlikely since the days of shop cards have long gone by) for a shop to teach a course that did not meet NAUI Standards (let's make it extreme, offer a course that was not taught by a certified instructor of any sort) and at the end issue a shop card. Then they could bring in a NAUI Certified Instructor who could administer a written exam and who make a single O/W dive with the student and issue a NAUI entry level credential. NAUI has closed this gap by requiring a log of 25 dives, a written exam and all four dives (which I'm sure pisses off the Navy guys for whom this clause was originally designed). I do not know if this is the standard that is in effect in SA, because there has been a separate NAUI South Africa organization since the late 1990s.
My only point was that the shop owner could respond (giving the older NAUI Standard) that the student was certified as a diver (shop card, the X-certification) with no dives (that was common in the old days, O/W was optional) and that he did all the required skills during his one and only dive. Shady business, but do you see the possibility?
Also, one of the open question here is, regardless of what the LDS owner's affiliations are, what certifications did the instructor hold?