Multichoice Threatens to Black list me after cancelling subscription

I was a premium DSTV Subscriber and I cancelled my DSTV subscription in January This year. I walked in to the DSTV customer centre in January with my 2 DSTV Explora decoders as both were not working. The consultant told me that the decoders hard drives were faulty and I either get them repaired or get new ones. I was not prepared to spend again on Exploras as every few years I have to buy new exploras due to the hard drives going faulty. So I asked the consultant to cancel my subscription to DSTV on the 23rd of January. She said cool and she will put an instruction to cancel at month End as I paid in full at the beginning of the month. Now I am getting harassed by their legal collections company Norman Bisset Attorneys threatening to black list me because I owe multichoice 150 rands. This is such a joke that Multichoice is trying to ****** 150 rands from me by threatening me with black listing me after I cancelled my subscription. Are they that desperate to collect money to keep their business afloat jeopardising customer relations. I thought that if I was not happy with my other streaming services that I will go back to DSTV, but now, after threatening to black list me, I don't think I will ever deal with Multichoice again.