Vodacom bad service provider for fibre

We put in fibre with vodacom 500/200 line. From day one we don't get the speed we are paying for. The highest we got was 203/200. Why do I need to pay for something that I'm not getting. We send emails after emails daily with no reply. We speak to customer care from Vodacom they just open tickets and closes them the whole time. Vodacom was at our house and vumatel but still the problem is not solved. The one blames the other one. I can't pay for something that I'm not getting. I really need somebody to get back to me and get this problem solved.