Shocking service and insensitivity from Vodacom

Four weeks ago my brother tragically passed away. I assisted him a few years back when he needed a cell phone contract and took it out in my name to try and help him. I have been trying to call Vodacom with no response for over three weeks, tweeted them daily, and they keep saying they will come back to me. I want to cancel this contract and understand it may be difficult to prove my brother used it, but all I am trying to do is find out how to cancel and if I have to pay a penalty, I will do so! But at this extremely sensitive time for me, and very stressful, in wrapping up all his accounts etc, I have received zero support from Vodacom and it is making me extremely angry and uneasy. Please somebody help. Thank you