Dstv account

Multichoice does *****!! We checked our balance and it showed an amount of R557 then we immediately paid but noticed that the dstv is still disconnect and I immediately contacted them. They busy telling me I must pay an extra R479 that we had an overdue of R400 and something and my question is why were we not shown the whole amount if that's the case?? I mean this is not the first time we take a break from paying dstv we always do and at no point we had overdue payments I mean for what?? The dstv is disconnected anyways, the most annoying part is the part that they showed us that R558 and then after paying they telling us to add more why??? Is there no law that says you pay for the price you were shown?? How do I go about this??