DSTV keep deducting from my account after contract ended

My DSTV contract ended 2 months ago and I cancelled my services well in advance. On the 26th of February DSTV deducted R937.22 from my account after I gave them an instruction to cancel my debit order. Failure to give me a refund or reverse the money I told them to continue for 1 month. This month (March 26th) another full premium deducted. I don't want a credit, I want my money back (full refund). I also gave an instruction for DSTV to NEVER deduct my account again but the still went ahead.