been charged so much that im no longer what im paying for

I have 2 decoders both with extra view, in October i upgraded the one to premium and in December I upgraded the other decoder. So i was paying for 2 decoders both on premium. then in January, my service on the one decoder was downgraded without my knowledge. i then called in to inquire about the problem and was told that it was a system error. my account was then upgraded. Earlier in January i also upgraded to dstv explora meaning that i now have an explora with extra view and a decoder on premium also on extra view. When my explora was activated i was told that R200 would be used as pro rata meaning i would not be paying the R959 for the end of January. To my surprise, i receive an sms informing me that i should pay an amount of R885 by the 11th february. i call again and the agent tells me that its a mistake and i should only pay R445 and she explains how this amount came about. I then pay the money and again receive an sms that this amount was not sufficient and i should pay an additional R105. now this leaves reeling because exactly how much am i being charged by multichoice. to my understanding the extraview on explora is free meaning my bill should amount to R1800 a month, thus far i have paid R1950 and still owing. Through the years that i have been a customer, never have i experienced such disservice.