Has Eskom been ****ming me for years?

I received my April 24 account from Eskom for R3350 (1790 units). The account was paid and I sent Eskom an email requesting that they send someone to unlock their meter box to confirm that the reading was correct. If I might add, myself and my wife are both in our 70's and we use electricity very sparingly I received a call and the person then rerouted the email to another Dept which then gave a garbled rejection reply in an email. I then took a closer look at the April 24 account and saw that the incorrect opening reading was used. They had taken the opening reading for March's account, which had been paid, and then added the closing reading for April. This means that I was charged twice for the March account, I.e. I was charged for 3 months over a 2 month period. Now, we have received accounts like this in the past and just paid it without examining the opening and closing readings and this now begs the question, has this occurred multiple times over the 30 year period we have lived on our property. I would therefore humbly have to request that each and every account for the past 30 years be checked to confirm it's correctness, because the abnormally high accounts we have received in the past now begin to look suspicious.