NOT getting what I am paying for

I have been having slow speeds now for almost a year. Metrofibre has upgraded the lines to 500/500. Every month I have a drop in speed on my line. I keep logging calls but this does not get sorted. There has been 3 technicians at my house and they have found nothing wrong with my connection. But the connection still flaps, one day it is 500/500 then it drops to 100/50. For the last month my connection has been 500/80 and this does not get resolved at all doesn’t matter how many calls I log there is no resolution to the problem. I logged a call on Saturday 3 December 2022 and no one at Afrihost has even acknowledged the call. I sent a message today 5 December 2022 to the same call asking when someone is going to pick up the call. I am totally disgusted in the willingness of Afrihost to resolve calls, if they do not close it before the resolution they just don’t respond. If they do respond it is with the normal scripted mail without even reading the call that is logged. My line has been 100/50 for the last 3 days and no response. I would expect Afrihost that is my service provider to resolve any issue with Metrofibre. On the previous calls that were logged where Metrofibre phoned me they say the problem is with Afrihost that is throttling the line even though when I took the service this was clearly stipulated, no throttling or shaping. Afrihost seems to believe it is Metrofibre and I am sitting in the middle with no resolution and getting very irritated that Afrihost cannot resolve the issue.