Herotel gives half or less the speed that they charge for

I got a 200mb/s package from Herotel Cloud Karoo in Middelburg EC. So I'm paying for that package but since I got fibre in March untill now I only get maybe 100mb/s. I asked herotel to downgrade my package to the speed that I'm getting on speedtest but they still didn't even make an effort to contact me in this regard. I can't pay for something I don't have