Unauthorized Debit Order Deduction.

I contacted Dstv for the Pricelock deal of R899. They delivered a decoder and a WiFi connecter to me. I do not have WiFi. For the next 4 months they deducted the monthly payment for two premium accounts from my bank account (I pay by debit order) The pricelock Decoder was installed last week and the initial subscription was canceled. I wanted them to either refund me or not deduct for the next four Months. I received an e-mail stating that they bill you as from delivery date and cannot refund me nor give me a freebie for the next 4 months - I should not have delayed installation.