Opt out doesn't work. Not compliant with POPIA

I've never signed up or Googled this service, yet I get up to 10 calls from them daily. I've mailed he opt-out email, but it can't be delivered because there's something wrong with their server. Can't online opt-out because it keeps "failing". UNWANTED CALLS, POPI ACT, HOW THE H*LL DO THEY WANT US TO OPT OUT TO SOMETHING WE NEVER OPTED IN FOR?!?!