Problems with fibre internet

I'm very upset and disappointed in the quality of the fibre internet. Since January / February 2021 and especially since the middle of June 2021 (more or less), the quality of the internet has been well below par right through the whole day with the internet speed fluctuating constantly. The streams would work ok-ish during the day, with the streams buffering here and there which I guess is alright and I guess you can suck it up and deal with it. However, especially in recent times and especially in the evenings from 6pm - 11pm more or less, the buffering has no end in sight. I also enjoy PC gaming, however this is not possible anymore as of late as I keep getting packet loss and inexplicable ping spikes (at any given time but especially in the evenings). I even used WINMTR (which MindTtheSpeed recommended us to use when we logged a call to be able to see ping, loss, etc). and it clearly shows ping spikes and packet loss of up to 20% which is unacceptable when it comes to gaming. Previously MindTheSpeed's answer was that they would see nothing wrong on their end and we should give them another chance as they (at the time we logged the call which was logged in April / May), apparently did a major upgrade for Cape Town. This has still not been fully resolved 2 months later. My packet loss and high ping was managable at the time we logged the call and playable at 1 or 2% packet loss and some ping spikes of 60 ms once in a while with the help of QoS (the only thing that made the ping / loss slightly better). Now, however, from around mid June 2021, QoS doesn't even help anymore. As explained above, I sometimes have packet loss of up to 20% and ping spikes of up to 100ms on local servers which are located in Johannesburg - I'm situated in Cape Town. It's really frustrating and enfuriating and it's really becoming more and more unpleasant. We did everything we could possibly do from our end.

As mentioned above, earlier in the review, the packet loss and ping spikes have been there since the start of this year but have become worse from around the mid June 2021. I must add, however, that there is also the possibility that the problem may be vumatel, however, I would appreciate it if MindTheSpeed or vumatel could kindly inform me as to where the problem lies or who is at fault, so I can at least have an idea of what is going on and to be able to better understand the situation.