payments on self service

nightmare... I paid my dstv on the wonderful self service website ... the amount due was R1148 as per the 2nd November and I paid with my card... on the 6th they disconnected me... I phone two days 40 min phone calls in total.. they found the "error" reconnected me on Saturday 11 November sms I owe them R835.78 and they are disconnecting me... on Monday another sms I short paid R189.49 .... they are going to disconnect me... the call agents says I am R2000 behind so what is going on .. if you refer a customer to self service and it says the amount due as per that date is R1148 how can it be wrong .. just a nightmare service