Prepaid Electricity - Service Charge Confusion?

If i was aware that using FNB buy electricity would occur a 50.00 Service fee, i would not have been using FNB's services.

To put this in contect when the payment services worked before (which many times it did not work) i was charged in the following maner: Dates: 2017/09/3 & 2017/08/17 & 2017/07/31 Amount: R500 Service Fee: R 0 Units Received: 218.30 Cost Per Unit: R2.29

Since just buying Electricity Date: 2017/10/29 Amount: R500 Service Fee: R50 + 2.30 added to my credit card Units Received: 218.30 Cost Per Unit: R2.53

That is a total of 10% Increase in tarrif costs... and that is only by the service fee incured? No tangable benefit to me.

Now either there is an disclosure problem, and the R50 rand has been deducted from my account before (via the the purchase initially) - and i only received R450 electricity and the R50 rand was baked into the costs and they only now inform me of the costs now, making my latest purchase the same cost per unit as before. Or as i understand it the R50 rand will be deducted later on?

Please FNB help me understand this whole con-deluded plot.