Terrible billing service

I am really frustrated with RSAWEB. my account is always in arrears. My statement shows R0 to be paid then out of the blue I have to pay double. I have proof that my statement shows R0 but now I'm told I have to do a double payment. That is very unprofessional. Every month I have a problem with this company. Why do you guys not do your job properly. February showed R0. March is not even on the statement. Someone need to sort this out. If my statement shows R0 then why must I pay double now. It is the company's fault