Vodacom Terrible Customer service

Vodacom and Bytes technology again with terrible rude customer service. I get a call from an upgrade consultant who lies to me saying he works for Vodacom when actually he works for Bytes technology, he offered to upgrade my contract so I said I would like to look around before I settle and call them back, he rudely said OH you can't call me back, you must pay extra from next month. Again my question is Why is my details being given to other service providers when Vodacom is taking my money every month, Why is Vodacom allowing their clients to be treated like this.