Really patronising

People from this company keep calling my number which is not even in contract with, insisting on an upgrade that even vodacom doesn't even know I've made an agreement with. After call and every week they keep on calling with a Durban number and a 087 number insisting on the same thing. This is really irritating and the agents have an attitude just keep on pushing for something I don't want. If vodacom can't stop them then I suppose a case of badgering will be opened against them. If the contract expires then so be it. And why are they calling on behalf of vodacom to sell something I'm not even interested in.