WARNING: Do not accept municipal prepaid meters from just anyone off the street for cash, even if they claim to work for or in a council/municipality. As of late there are too many scams being reported in South Africa and specifically Joburg in this regard. There are people who claim to work for municipalities and get meters for you; which are either stolen from a municipality or not municipal meters, nor connected to any municipality or vending system. They usually take cash and disappear.
The more advanced scams will remove your legal meter and put a fake municipal prepaid meter that is not connected to anything. This will leave you liable for the real electricity consumed until you find out it is not connected.
You will soon know the meter is illegal when you get a letter of demand from the municipality.
If you fall prey to one of these scams you will not be able to get your money back and you will be obligated to return the meter to its rightful license owner, which is probably the property of a municipality from which it was stolen in the first place. In addition to which you will remain liable for the electricity consumed until such time as you get a new legal post-paid or prepaid meters.