DStv Bill

Okay so now I'm very very confused and the Agents seems to be confused maybe someone else will be able to explain this for me. So I changed my debit date to the 10th for December and I was told of a pro rata which I had paid as on the 10th I called again to change my debit date to the 16th as I lost my mother but I still paid the pro rata again so on the 16th I changed it to the 26th of December and I paid a full amount after paying these pro rata amounts so when I pay a full amount to my understanding and knowledge my next payment is on the 26th of the next month which is January. What I don't understand is why is it that my payment increased to R645 instead of my normal monthly fee of R538 per month as I am not owing dstv anything and I paid my prp ratas I was told to pay I am very disappointed and I really don't understand and I am not getting a proper explanation. Yoh I'm really tired of the way dstv is treating us customers and the Agents just have no time I was on a Facebook chat most of the time as the Agents are just so rude on calls