Vodacom harrasing customers with unwanted SMS messages

I've been trying to block Vodacom's competition and subscription SMS messages for 3 weeks now, with no luck. I used the USSD code and chose the option NOT to receive any marketing communications, etc., and I choose the STOP option whenever I receive these unwanted messages, but it does not stop. Is this even legal? Surely the POPI Act should protect Vodacom's customers from receiving these messages as some are actually messages from 3rd parties and not Vodacom? The POPI Act also gives me the right to choose if I want to receive anything? I shouldn't be wasting time to try and block these messages, I never gave Vodacom permission to abuse my number in the first place. The Vodacom pop-up messages should also stop, if you don't look carefully you could be subcribed to anything...