Shocking customer service

Lies upon lies and no service. We had fibre installed at the end of July, 10mb line. We have NEVER gotten 10 mb speed on that line. Sometimes it doesn't work at all. It's a nightmare trying to get any help (on weekends no-one answers at the call centre). Tried getting help through the whatsapp line, it takes hours for them to respond. They insist on me doing everything I've done 6 times before calling (switching on and off, etc). Only then will they refresh the connection from their side, which helps for maybe half a day before the problems start up again. (We have had Vumatel out to test the line, it's not faulty). They refuse to escalate the matter. They promise to call back, they never do. Worse than the speed is the fact that the connection keeps dropping out. It's so unstable we have to have to go on mobile connection for conference calling (what's the point of fibre then?) To try and mitigate this, we decided to upgrade to a 20mb line. They said it would take 24 hours. It's 5 days later, it's still not done. They now say it will take another 24 hours, they had a system error. They refuse to escalate. They refuse to let me speak to a manager. I am at my wits end.