Please stop calling me - DSTV Multichoice Telemarketing and Cold Calling

DStv (MultiChoice) telemarketers keep calling me with offers to join at a discount. I've opted out from all direct marketing channels and this still persists. I've asked the agents to stop calling and to remove me from their systems and that I do not give them permission to call me, yet they still call multiple times per day. This is harassment and should be investigated by the relevant government departments.

Plus these agents are extremely rude. These call centers should be shut down!!