Inflated billing

I called the Sabc querying my account balance the call centre agent assisting me refused to give me his name. I wanted to know how come I am owing about R600 when I have paid up the account with only the 2017 amount owing. I have been waiting for about 3 weeks since the agent told me he d follow up my query. Can the Sabc please stop sending me payment reminders until my request has been attended to