Vodacom **** Agents

Good day I am not complaining about the network.

What I do have a problem with is the number of "Vodacom agents" continuously phoning to "upgrade your line" for better pricing. I have been cought once and Vodacom did fix it. My problem is why are they allowed to exist and why do they have access to my personal details that I trusted Vodacom to protect. And how on earth do they manage to get so many telephone numbers to use. I hope someone from Vodacom will respond.