DSTV *****ing R 200 every month

So I signed up for a price lock deal of R899 in March. April R1155 deducted from my bank account. Phoned them, apparently someone in my household signed up for Netflix (Which I already have a premium subscription for), asked them to cancel it, and I checked my ultra decoder, it is indeed, my personal subscription that is signed in. Come end of May, again R1155 deducted form my account. Again, Netflix... How do you cancel something, if you don't even know the sign in details or sign up email or cellphone number? This is utter bull****. I'm paying for something, that I DONT WANT, DONT NEED, AND DIDN'T ASKED FOR!