Over charging

I received an sms saying that an amount of R795.00 is due. Could someone please tell me when the price increased from R300.00 to R800? Or is it a case of stupidity on the part of the sabc. I paid my licence last year (still to not have anything to watch on sabc) and still i get told i have not paid, now you have accumulated interest on an account that is up to date. If there is someone competent enough to do basic maths, I would appreciate it if my account can be sorted and I will not be paying anything until this over charge is rectified. And please also explain how an account can be due right in the middle of the month, when i said that i get paid at the end of the month.