GREENPEACE AFRICA STOP CALLING ME!!!

I have never dealt with Greenpeace Africa nor am I interested to. Never subscribed to any of their materials yet they spam call me almost EVERYDAY about 10 times per day. I have blocked them but they keep spamming my phone. I need them to STOP IT cos I'm on the verge of reporting them for violation of POPI ACT as I don't know where they got my details from. They are a pain to be honest, even if I was going to subscribe to their cause, now I WILL DEFINITELY NOT!! This is truly bordering on harrassment!!! They must stop harassing me!!!