High ping/ Low speeds

I have been with Metrofibre for 2 years. In the past 6 months we have been having latency issues from the afternoon till midnight. I call in and within an hour or so they used to sort it out temporarily and the next evening the same issue again. I had to keep calling daily. Very costly on calls. From the 22 November, they were unable to sort it out and the issue persisted for 4 days straight, eventually they sorted it out and it was fine for one day but that same evening there was high ping again and low speeds. I called in again on the 26 November and got a reference 496858 for this latency/ping and speed issue with wifi/lan from the afternoon of each day till midnight. It's unusable. But from midnight till the nex day it's perfect. On the 26 November it was forwarded to the Ops department and they said they would sort it out with 24 hours and give me a call. It's been 11 days now and nothing is sorted and no one from ops has called. They just keep emailing each morning that my internet is fine. Are they uneducated?? Can they not understand or acknowledge that the issue starts in the afternoon and ends at midnight. That's when ppl are home from work/school and need to use their internet. Our home gets completely shut off from using it cos other houses here seem to be prioritized. This issue was happening randomly but not completely stuck like this each day. If I had to pinpoint a time this started getting so drastic, it would be from the first week of October a technician changed the cable in the area, we were gone offline for 2 days cos he incorrectly reconnected us, then he came back and put in another cable and moved us over to that cable, it seems that too many houses are running off that one Fibre optic. Or it could be that you guys sold too much bandwidth to other ISPs and now your clients are suffering during peak hours. 4pm till midnight. It been 11 days since someone was supposed to call me from Ops department but no one has bothered to sort out the issue or call me. I've called, whatsapp and emailed repeatedly with no joy. This is not ethical. I expect to get what I pay for but so far I've been spending more money and time on trying to get this sorted.