Dstv price lock problem

I have taken a 24 months contract with dstv price lock in June, they promised to deliver a new decoder according the contract of which I still have another existing at home.

2-3 weeks passed without delivering the decoder but month end money was deducted on my acc. I tried to call them with no luck, fortunately they called me back telling me that the decoder was returned because the courier guy couldn't find my address, but they will resend it they will tell the courier guy to call me.

Fine I expected it again but another month down the line... no decoder but money was deducted and was not found. Now this morning my dstv is closed because they said i did not pay my dstv o f which i paid R570 on the 30July. Now they want me to pay for a price lock contract without receiving the decoder and is not even connected in my house, i dont even know how it look like. Now my kids can't watch tv because they say i owe price lock that i dont have but i paid my normal explorer. My point is how can they deduct money for something that I don't have. Please help