Subscription change without my knowledge.

I haven't used my dstv in a long time almost 2 years if not more but when i paid for my subscription this year i was told that i changed to premium package. How can i change to premium package whereas i have not used my Dstv in months. I paid for that premium and last month i cancelled that subscription but there is still an additional +/- 250 that i owe excluding the compact package that i need to pay for. This is absurd i need my money back. Im supposed to pay for my subscription today but i cant coz i owe money that i dont know about.