VOX poor service and line speed

Besides VOX just arbitrarily changing your (expected) line speeds and then the associated billing, they are extremely slow in responding to queries. My ups had issues and it took them MONTHS to get back to me. I eventually gave up and then, out of the blue, they just called. My main issue now is that I am paying for a 50mb up and down line, but never get the 50 down. It has been as bad as 1-2mb down at stages and max is about 35mb. It is also very unstable. My query regarding this has now been sitting with them for 3 days, with no further feedback. How can they charge you a premium for something they do not provide? That is *********. Very unhappy and very disappointed. Maybe VODACOM fiber will be better.