Telesales trying force deals on you

I recently upgraded via Vodacom direct and got a new blacberry keyone. Reading reviews afterwards o the internet i became aware that there is a problem with the microphone and the person you speak to cant hear your clearly. Vodacom refuse to take the phone back and let me choose another phone. Today vodacom call me trying to force me into a new contract for my other account. I insisted that they must email me this so called special thats not available in stores and the agent refused.