Very slow and terrible service

I pay for a 1000MBps fiber line R1499 per month and I am only getting less than 100MBps, I am not paying (R149) 10%, I am paying (R1499) 100%. I have a macbook pro with no lan ports, other than that I have 4 other devices and all 4 is less than 100Mbps. The service provider is VUMATEL, Can we discuss a refund and cancelation for alll other services worth R3500 per month. The Lan connector is R800, you can bring one and install it on my macbook pro and then check directly and then get a screenshot to get vumatel to do there job, it is your modem or your cable that is faulty, I don't want to reset my modem, I want my 1000Mbps per Month:(