UPNORMAL ELECTRICITY BILL

IN JANUARY WE MADE A PAYMENT OF R1000 AND I CALLED IN TO CHECK THE ACCOUNT THEY SAID THE ACCOUNT WAS NOT IN ARREARS JUST A FEW WEEKS LATER THE STATEMENT COMES WITH A TOTAL OF R2350.00, HOW DO THEY BILL? BECAUSE THEY ARE BILLING IS BECOMING CRAZY EVERY MONTH.<br>