This seems to be happening not only in the Electricity vending space but also in the Airtime space. I recently was quite surprised to see a notice on a shop wall that said there will be a R1 surcharge for prepaid airtime vouchers.
The problem in the electricity space stems from the low commissions vendors are paid which then forces them to find alternative ways to gain extra income. There also exists the turnaround time that vendors have to wait to be paid. Further to this certain vendors have to pay a rental on the terminals that they use to sell the electricity.
Super/National Vendors are well suited to selling electricity through the chain stores where sales are done just to be able to provide a full basket of services to their shoppers, in which case the low commissions is not a major issue.
However recently Super Vendors are doing vending outside of the chain stores and the vendor's they use derive their income solely based on the sales of Electricity.
When you consider that on average a vendor receives between 1.25% and 2% commission, they could receive between R2500 and R4000 on Sales of R200 000. Based on existing purchasing history this equates to an average of about 10 000 Sales. Assume an 8 hour working day, 6 Days a week and a 4 Week Month which equates to 192 Hours of Sales. Now this then equates to 52 Sales an Hour with roughly translates into a full time job. Now also consider the fact that the vendor has to pay upfront for the credit before they can sell it which also translates into numerous trips to the banks to make deposits weekly if not daily and they take the risk for the cash.
I am in no way justifying the vendors actions but highlighting some of the reasons they resort to these kind of measure and hopefully once we understand the cause we can work towards a solution.