Unable to credit my account

In March I was charged twice the amount of R709 on my account. I contacted ESKOM to rectify this , the day I received the invoice in March but to date I had no response from them. Every time I call them they log a new call but no one ever came back to me. Meanwhile, every month I get charged interest on my account for that amount still \outstanding"and instead of helping they sending their contractors out to disconnect my box. This is very frustrated and I want this sorted immediately. <br> <br> I want to be issued with an updated invoice"