Afrihost are ka****

I pay for a 20mbps premium uncapped fibre line. This means that I should not get throttled or shaped. There have been a few once off issues in the past, usually fixed within 2-3 working days, but recently Afrihost have turned to the pits. I pay R1017 a month for my 20mbps line. For the past 10 days I have been receiving a maximum of 8 but averaging around 5. These tests have been done over wifi and through a laptop connected via ethernet cable to the modem and test directly from laptop to CPE. All of them producing the same results. Afrihost are blatantly refusing to fix my issue and just keep saying "everything looks fine on our side". I'd love to know what would happen if I only paid R254.25. They would cancel or suspend my contract. What gives them the right to take my money but not provide what I am paying for. I will definitely be taking this further should I not receive a reply and my issue resolved.