Worst billing system ever - no accountability

Earlier this year i moved my subscription with DSTV to a smaller deal. I asked that the move take effect on the 25th of the month as this is when my payment is made. i then changed to a different packaged again after a couple of months. Now suddenly my account has been blocked 3 times in 2 months. every month on the 25th i make my payment as per the sms received from DSTV. how can my account then be in arrears. I have called the call center and no one can help. the cannot email me a break down of my account and i have not received any invoices from them. the last time i called in i was given one amount that I am "in arrears" with by the agent. then a few minutes later I received an sms with a different amount and when my account was cut again and sms with yet another amount. does anyone there know what is going on? no managers are ever available. your never get a straight answer from the staff and no recorded calls can ever be traced.