stranded Mozambiquans

In the last couple of months I have received calls from 2 separate friends, who have met up with stranded Mozambiquans, in Zim. They have a long story to tell about how they have broken down/run out of fuel, and require some dollars to get them on there way. They appear to have done some research, and can name drop convincingly.i.e. your name, your spouses name, maybe some business associates etc. They offer their bosses names, and phone numbers, (Vilankoulos, seems to be the place), who will only be too delighted to refund.  etc etc. On both occasions I have called the numbers, and they are either not reachable, or no longer in use, and I have called friends living in those areas and they have never heard of the "boss". If someone is feeling charitable, ask to see their passport ( 'Sorry, I've left it in the car, or with a friend').